shadow_mapping_cascade.c

// https://github.com/Flix01/Tiny-OpenGL-Shadow-Mapping-Examples
/** License
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
*/

// DEPENDENCIES:
/*
-> glut or freeglut (the latter is recommended)
-> glew (Windows only)
*/

// HOW TO COMPILE:
/*
// LINUX:
gcc -O2 -std=gnu89 -no-pie shadow_mapping_cascade.c -o shadow_mapping_cascade -I"../" -lglut -lGL -lX11 -lm
// WINDOWS (here we use the static version of glew, and glut32.lib, that can be replaced by freeglut.lib):
cl /O2 /MT /Tc shadow_mapping_cascade.c /D"GLEW_STATIC" /I"../" /link /out:shadow_mapping_cascade.exe glut32.lib glew32s.lib opengl32.lib gdi32.lib Shell32.lib comdlg32.lib user32.lib kernel32.lib


// IN ADDITION:
By default the source file assumes that every OpenGL-related header is in "GL/".
But you can define in the command-line the correct paths you use in your system
for glut.h, glew.h, etc. with something like:
-DGLUT_PATH=\"Glut/glut.h\"
-DGLEW_PATH=\"Glew/glew.h\"
(this syntax works on Linux, don't know about Windows)
*/

//#define USE_GLEW  // By default it's only defined for Windows builds (but can be defined in Linux/Mac builds too)


#define PROGRAM_NAME "shadow_mapping_cascade"
#define VISUALIZE_DEPTH_TEXTURE
//#define VISUALIZE_CASCADE_SPLITS
#define SHADOW_MAP_HEIGHT 512               //SHADOW_MAP_WIDTH = SHADOW_MAP_NUM_CASCADES*SHADOW_MAP_HEIGHT
#define SHADOW_MAP_NUM_CASCADES 4
#define SHADOW_MAP_CASCADE_LAMBDA   0.7     // in [0=uniform splits,1=logarithmic splits] logarithmic splits put higher resolution near the camera
#define SHADOW_MAP_CLAMP_MODE GL_CLAMP_TO_EDGE // GL_CLAMP or GL_CLAMP_TO_EDGE or GL_CLAMP_TO_BORDER
    //          GL_CLAMP;               // sampling outside of the shadow map gives always shadowed pixels
    //          GL_CLAMP_TO_EDGE;       // sampling outside of the shadow map can give shadowed or unshadowed pixels (it depends on the edge of the shadow map)
    //          GL_CLAMP_TO_BORDER;     // sampling outside of the shadow map gives always non-shadowed pixels (if we set the border color correctly)
#define SHADOW_MAP_FILTER GL_LINEAR // GL_LINEAR or GL_NEAREST (GL_LINEAR is more useful with a sampler2DShadow, that cannot be used with esponential shadow mapping)

//#define USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE   // Better resolution, but shadow-swimming as the camera rotates (on static objects). Please see README.md about it.

// Warning: This is one of the demos that supports switching from perspective camera view to ortho camera view [F1 key].
// However please note that in ortho view the shadow mapping algorithm is currently ALWAYS a bit unstable (even if USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE is not defined).
//
// The reason is that I've tried just using the 'perspective' version of the shadow map algorithm and it does not work correctly for cascaded shadow maps (it worked well in non-cascaded shadow_mapping.c).
// That's why Helper_GetLightViewProjectionMatrices(...) takes one more argument than Helper_GetLightViewProjectionMatrix(...): 'cameraTargetDistanceForOrtho3DModeOnly_or_zero'.
//
// Ideally it should be called 'cameraTargetDistanceForUnstableOrtho3DModeOnly_or_zero', but in the case of cascaded shadow maps if we set it to zero (= we use the same algo used in perspective mode for ortho mode)
// it does not work. That's why ortho mode is currently always a bit 'unstable' for cascaded shadow maps (well, less unstable than defining USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE, that works as expected).
//
// Hope this point is clear enough...


// These path definitions can be passed to the compiler command-line
#ifndef GLUT_PATH
#   define GLUT_PATH "GL/glut.h"    // Mandatory
#endif //GLEW_PATH
#ifndef FREEGLUT_EXT_PATH
#   define FREEGLUT_EXT_PATH "GL/freeglut_ext.h"    // Optional (used only if glut.h comes from the freeglut library)
#endif //GLEW_PATH
#ifndef GLEW_PATH
#   define GLEW_PATH "GL/glew.h"    // Mandatory for Windows only
#endif //GLEW_PATH

#ifdef _WIN32
#	include "windows.h"
#	define USE_GLEW
#endif //_WIN32

#ifdef USE_GLEW
#	include GLEW_PATH
#else //USE_GLEW
#	define GL_GLEXT_PROTOTYPES
#endif //USE_GLEW

#include GLUT_PATH
#ifdef __FREEGLUT_STD_H__
#   include FREEGLUT_EXT_PATH
#endif //__FREEGLUT_STD_H__

// These derived definitions can't be touched [XSTR_MACRO(...) is used to insert an 'integer definition' between double quotes]
#define STR_MACRO(s) #s
#define XSTR_MACRO(s) STR_MACRO(s)
#define SHADOW_MAP_NUM_CASCADES_STRING XSTR_MACRO(SHADOW_MAP_NUM_CASCADES)
#define SHADOW_MAP_WIDTH (SHADOW_MAP_HEIGHT*SHADOW_MAP_NUM_CASCADES)    // Fixed


#include "helper_functions.h"   // please search this .c file for "Helper_":
                                // only very few of its functions are used.

#include <stdio.h>
#include <math.h>
#include <string.h>


// Config file handling: basically there's an .ini file next to the
// exe that you can tweak. (it's just an extra)
const char* ConfigFileName = PROGRAM_NAME".ini";
typedef struct {
    int fullscreen_width,fullscreen_height;
    int windowed_width,windowed_height;
    int fullscreen_enabled;
    int show_fps;
    int use_camera_ortho3d_projection_matrix;
} Config;
void Config_Init(Config* c) {
    c->fullscreen_width=c->fullscreen_height=0;
    c->windowed_width=960;c->windowed_height=540;
    c->fullscreen_enabled=0;
    c->show_fps = 0;
    c->use_camera_ortho3d_projection_matrix = 0;
}
int Config_Load(Config* c,const char* filePath)  {
    FILE* f = fopen(filePath, "rt");
    char ch='\0';char buf[256]="";
    size_t nread=0;
    int numParsedItem=0;
    if (!f)  return -1;
    while ((ch = fgetc(f)) !=EOF)    {
        buf[nread]=ch;
        nread++;
        if (nread>255) {
            nread=0;
            continue;
        }
        if (ch=='\n') {
           buf[nread]='\0';
           if (nread<2 || buf[0]=='[' || buf[0]=='#') {nread = 0;continue;}
           if (nread>2 && buf[0]=='/' && buf[1]=='/') {nread = 0;continue;}
           // Parse
           switch (numParsedItem)    {
               case 0:
               sscanf(buf, "%d %d", &c->fullscreen_width,&c->fullscreen_height);
               break;
               case 1:
               sscanf(buf, "%d %d", &c->windowed_width,&c->windowed_height);
               break;
               case 2:
               sscanf(buf, "%d", &c->fullscreen_enabled);
               break;
               case 3:
               sscanf(buf, "%d", &c->show_fps);
               break;
               case 4:
               sscanf(buf, "%d", &c->use_camera_ortho3d_projection_matrix);
               break;
           }
           nread=0;
           ++numParsedItem;
        }
    }
    fclose(f);
    if (c->windowed_width<=0) c->windowed_width=720;
    if (c->windowed_height<=0) c->windowed_height=405;
    return 0;
}
int Config_Save(Config* c,const char* filePath)  {
    FILE* f = fopen(filePath, "wt");
    if (!f)  return -1;
    fprintf(f, "[Size In Fullscreen Mode (zero means desktop size)]\n%d %d\n",c->fullscreen_width,c->fullscreen_height);
    fprintf(f, "[Size In Windowed Mode]\n%d %d\n",c->windowed_width,c->windowed_height);
    fprintf(f, "[Fullscreen Enabled (0 or 1) (CTRL+RETURN)]\n%d\n", c->fullscreen_enabled);
    fprintf(f, "[Show FPS (0 or 1) (F2)]\n%d\n", c->show_fps);
    fprintf(f, "[Use camera ortho3d projection matrix (0 or 1) (F1)]\n%d\n", c->use_camera_ortho3d_projection_matrix);
    fprintf(f,"\n");
    fclose(f);
    return 0;
}

Config config;

// glut has a special fullscreen GameMode that you can toggle with CTRL+RETURN (not in WebGL)
int windowId = 0; 			// window Id when not in fullscreen mode
int gameModeWindowId = 0;	// window Id when in fullscreen mode

// Now we can start with our program

// camera data:
float targetPos[3];         // please set it in resetCamera()
float cameraYaw;            // please set it in resetCamera()
float cameraPitch;          // please set it in resetCamera()
float cameraDistance;       // please set it in resetCamera()
float cameraPos[3];         // Derived value (do not edit)
float vMatrix[16];          // view matrix
float cameraSpeed = 0.5f;   // When moving it

// light data
float lightYaw = M_PI*0.425f,lightPitch = M_PI*0.235f;    // must be copied to resetLight() too
float lightDirection[4] = {0,1,0,0};                    // Derived value (do not edit) [lightDirection[3]==0]

// pMatrix data:
float pMatrix[16];                  // projection matrix
const float pMatrixFovyDeg = 45.f;
const float pMatrixNearPlane = 0.5f;
const float pMatrixFarPlane = 20.0f;

// we calculate these in ResizeGL(...)
float gCascadeNearAndFarClippingPlanes[SHADOW_MAP_NUM_CASCADES+1];  // Array of the clipping planes of each cascade (gCascadeNearAndFarClippingPlanes[0]==pMatrixNearPlane and gCascadeNearAndFarClippingPlanes[SHADOW_MAP_NUM_CASCADES]==pMatrixFarPlane)
#ifdef USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE
float gCascadePMatricesInv[16*SHADOW_MAP_NUM_CASCADES]; // One inverse pMatrix per cascade (calculated in ResizeGL(...))
#endif //USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE


float instantFrameTime = 16.2f;

// Optional (to speed up Helper_GlutDrawGeometry(...) a bit)
GLuint gDisplayListBase = 0;GLuint* pgDisplayListBase = &gDisplayListBase;  // Can be set to 0 as a fallback.


static const char* ShadowPassVertexShader[] = {
    "   void main() {\n"
    "       gl_Position = ftransform();\n"
    "   }\n"
};
static const char* ShadowPassFragmentShader[] = {
    "   void main() {\n"
    "       //gl_FragColor =  gl_Color;\n"
    "   }\n"
};
typedef struct {
    GLuint fbo;
    GLuint textureId;
    GLuint program;
} ShadowPass;

ShadowPass shadowPass;
void InitShadowPass(ShadowPass* sp)	{
    sp->program = Helper_LoadShaderProgramFromSource(*ShadowPassVertexShader,*ShadowPassFragmentShader);

    // create depth texture
    glGenTextures(1, &sp->textureId);
    glBindTexture(GL_TEXTURE_2D, sp->textureId);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, SHADOW_MAP_FILTER);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, SHADOW_MAP_FILTER);
#   ifndef __EMSCRIPTEN__
    glTexImage2D( GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, SHADOW_MAP_WIDTH, SHADOW_MAP_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, 0);
#   else //__EMSCRIPTEN__
    glTexImage2D( GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, SHADOW_MAP_WIDTH, SHADOW_MAP_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_SHORT, 0);
#   undef SHADOW_MAP_CLAMP_MODE
#   define SHADOW_MAP_CLAMP_MODE GL_CLAMP_TO_EDGE
#   endif //__EMSCRIPTEN__
    if (SHADOW_MAP_CLAMP_MODE==GL_CLAMP_TO_BORDER)  {
        const GLfloat border[] = {1.0f,1.0f,1.0f,0.0f };
        glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, border);
    }
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, SHADOW_MAP_CLAMP_MODE );
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, SHADOW_MAP_CLAMP_MODE );
    glBindTexture(GL_TEXTURE_2D, 0);

    // create depth fbo
    glGenFramebuffers(1, &sp->fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, sp->fbo);
#   ifndef __EMSCRIPTEN__
    glDrawBuffer(GL_NONE); // Instruct openGL that we won't bind a color texture with the currently bound FBO
    glReadBuffer(GL_NONE);
#   endif //__EMSCRIPTEN__
    glFramebufferTexture2D(GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,GL_TEXTURE_2D,sp->textureId, 0);
    {
        //Does the GPU support current FBO configuration?
        GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
        if (status!=GL_FRAMEBUFFER_COMPLETE) printf("glCheckFramebufferStatus(...) FAILED for shadowPass.fbo.\n");
    }
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}
void DestroyShadowPass(ShadowPass* sp)	{
    if (sp->program) {glDeleteProgram(sp->program);sp->program=0;}
    if (sp->fbo) {glDeleteBuffers(1,&sp->fbo);sp->fbo=0;}
    if (sp->textureId) {glDeleteTextures(1,&sp->textureId);}
}


static const char* DefaultPassVertexShader[] = {
    "varying vec4 v_diffuse;\n"
    "varying vec4 v_vertexModelViewSpace;\n"
    "varying float v_vertexModelViewSpaceDepth;\n"  // A bit redundant (we can calculate it in the fragment shader using v_vertexModelViewSpace)
    "\n"
    "void main()	{\n"
    "	gl_Position = ftransform();\n"
    "\n"
    "	vec3 normal = gl_NormalMatrix * gl_Normal;\n"
    "	vec3 lightVector = gl_LightSource[0].position.xyz\n;// - gl_Vertex.xyz;\n"
    "	float nxDir = max(0.0, dot(normal, lightVector));\n"
    "	v_diffuse = gl_LightSource[0].diffuse * nxDir; \n"
    "\n"
    "	gl_FrontColor = gl_Color;\n"
    "\n"
    "   v_vertexModelViewSpace = gl_ModelViewMatrix*gl_Vertex;\n"
    "   v_vertexModelViewSpaceDepth = -v_vertexModelViewSpace.z/v_vertexModelViewSpace.w;\n"  // Negative, because camera looks in the -z axis (and u_cascadeNearAndFarClippingPlanes[...] are all positive quantities)
    "}\n"
};
static const char* DefaultPassFragmentShader[] = {
#   ifdef VISUALIZE_CASCADE_SPLITS
    "#version 120\n"
    "#extension GL_EXT_gpu_shader4 : enable\n"
    "#define NUM_CASCADES "SHADOW_MAP_NUM_CASCADES_STRING"\n"
    "const vec3 dbgSplitColors[4] = vec3[4](vec3(0.5,0.0,0.0),vec3(0.0,0.5,0.0),vec3(0.0,0.0,0.5),vec3(0.5,0.5,0.0));\n"
#   else //VISUALIZE_CASCADE_SPLITS
    "#define NUM_CASCADES "SHADOW_MAP_NUM_CASCADES_STRING"\n"
#   endif //VISUALIZE_CASCADE_SPLITS
    "\n"
    "uniform sampler2D u_shadowMap;\n"
    "uniform vec2 u_shadowDarkening;\n" // .x = fDarkeningFactor [10.0-80.0], .y = min value clamp [0.0-1.0]
    "uniform float u_cascadeNearAndFarClippingPlanes[NUM_CASCADES+1];\n"
    "uniform mat4 u_biasedShadowMvpMatrix[NUM_CASCADES];\n" // Actually they are: (u_biasedShadowMvpMatrix[NUM_CASCADES] * vMatrixInverseCamera) please see the code.
    "\n"
    "varying vec4 v_diffuse;\n"
    "varying vec4 v_vertexModelViewSpace;\n"
    "varying float v_vertexModelViewSpaceDepth;\n"
    "\n"
    "float CalcShadowFactor(int CascadeIndex, vec4 shadowCoord)   {\n"
    "   vec4 shadowCoordinateWdivide = shadowCoord/shadowCoord.w;\n"
    "   shadowCoordinateWdivide.x+= float(CascadeIndex);shadowCoordinateWdivide.x/= float(NUM_CASCADES);\n"
    "   return clamp(exp(u_shadowDarkening.x*(texture2D(u_shadowMap,(shadowCoordinateWdivide.st)).r - shadowCoordinateWdivide.z)),u_shadowDarkening.y,1.0);\n"
    "   }\n"
    "\n"
    "void main() {\n"
    "	// Figure out which cascade to sample from\n"
    "   float cascadeIdxFloat = float(NUM_CASCADES-1);\n"
    "   for(int i=1;i<NUM_CASCADES;i++)  {\n"
    "       //if (v_vertexModelViewSpaceDepth < u_cascadeNearAndFarClippingPlanes[i]) cascadeIdxFloat-=1.0;\n"      // branch!
    "       cascadeIdxFloat-=max(sign(u_cascadeNearAndFarClippingPlanes[i] - v_vertexModelViewSpaceDepth), 0.0);\n" // branchless!
    "   }\n"
    "\n"
    "   int cascadeIdx = int(cascadeIdxFloat);\n"
    "   vec4 lightSpacePos = u_biasedShadowMvpMatrix[cascadeIdx]*v_vertexModelViewSpace;\n"   // There's a hidden vMatrixInverseCamera multiplication that removes the view component, moving the mMatrix from the camera space to the light space
    "   float shadowFactor = CalcShadowFactor(cascadeIdx, lightSpacePos);\n"
    "\n"
#   ifdef VISUALIZE_CASCADE_SPLITS
    "   vec3 color = dbgSplitColors[cascadeIdx%4];\n"
#   else //VISUALIZE_CASCADE_SPLITS
    "   vec3 color = gl_Color.rgb;\n"
#   endif //VISUALIZE_CASCADE_SPLITS
    "\n"
    "	gl_FragColor = gl_LightSource[0].ambient + (v_diffuse * vec4(color*shadowFactor,1.0));\n"
    "}\n"
};


typedef struct {
    GLuint program;
    GLint uniform_location_biasedShadowMvpMatrix;
    GLint uniform_location_shadowMap;
    GLint uniform_location_shadowDarkening;
    GLint uniform_location_cascadeNearAndFarClippingPlanes;
} DefaultPass;

DefaultPass defaultPass;
void InitDefaultPass(DefaultPass* dp)	{
    dp->program = Helper_LoadShaderProgramFromSource(*DefaultPassVertexShader,*DefaultPassFragmentShader);
    dp->uniform_location_biasedShadowMvpMatrix = glGetUniformLocation(dp->program,"u_biasedShadowMvpMatrix");
    dp->uniform_location_shadowMap = glGetUniformLocation(dp->program,"u_shadowMap");
    dp->uniform_location_shadowDarkening = glGetUniformLocation(dp->program,"u_shadowDarkening");
    dp->uniform_location_cascadeNearAndFarClippingPlanes = glGetUniformLocation(dp->program,"u_cascadeNearAndFarClippingPlanes");

    glUseProgram(dp->program);
    glUniform1i(dp->uniform_location_shadowMap,0);
    glUniform2f(dp->uniform_location_shadowDarkening,80.0,0.45);	// Default values are (40.0f,0.75f) in [0-80] and [0-1]
    //glUniformMatrix4fv(dp->uniform_location_biasedShadowMvpMatrix, SHADOW_MAP_NUM_CASCADES /*only setting 1 matrix*/, GL_FALSE /*transpose?*/, Matrix);
    //glUniform1fv(dp->uniform_location_cascadeNearAndFarClippingPlanes,SHADOW_MAP_NUM_CASCADES,gCascadeNearAndFarClippingPlanes);
    glUseProgram(0);
}
void DestroyDefaultPass(DefaultPass* dp)	{
	if (dp->program) {glDeleteProgram(dp->program);dp->program=0;}
}

float current_width=0,current_height=0,current_aspect_ratio=1;  // Not sure when I've used these...
void ResizeGL(int w,int h) {
    current_width = (float) w;
    current_height = (float) h;
    if (current_height!=0) current_aspect_ratio = current_width/current_height;
    if (h>0)	{
        // We set our pMatrix
        if (!config.use_camera_ortho3d_projection_matrix)
            Helper_Perspective(pMatrix,pMatrixFovyDeg,(float)w/(float)h,pMatrixNearPlane,pMatrixFarPlane);
        else
            Helper_Ortho3D(pMatrix,cameraDistance,pMatrixFovyDeg,(float)w/(float)h,pMatrixNearPlane,pMatrixFarPlane);

        glMatrixMode(GL_PROJECTION);glLoadMatrixf(pMatrix);glMatrixMode(GL_MODELVIEW);

        // Here we calculate the splits (gCascadeNearAndFarClippingPlanes must contain SHADOW_MAP_NUM_CASCADES+1 elements) based on lambda, and camera near and far planes:
        Helper_GetCascadeNearAndFarClippingPlaneArray(gCascadeNearAndFarClippingPlanes,SHADOW_MAP_NUM_CASCADES,SHADOW_MAP_CASCADE_LAMBDA,pMatrixNearPlane,pMatrixFarPlane);
        // Here we update the uniform 'u_cascadeNearAndFarClippingPlanes' in the default pass shader program
        glUseProgram(defaultPass.program);
        glUniform1fv(defaultPass.uniform_location_cascadeNearAndFarClippingPlanes, SHADOW_MAP_NUM_CASCADES,gCascadeNearAndFarClippingPlanes);
        glUseProgram(0);

#       ifdef USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE
        // Here we fill float gCascadePMatricesInv[16*SHADOW_MAP_NUM_CASCADES]: (basically the inverse of all the camera projection matrices, one per split)
        {
            int i;
            for (i=0;i<SHADOW_MAP_NUM_CASCADES;i++) {
                float* pMatrixInv = &gCascadePMatricesInv[16*i];
                if (!config.use_camera_ortho3d_projection_matrix)
                    Helper_Perspective(pMatrixInv,pMatrixFovyDeg,(float)w/(float)h,gCascadeNearAndFarClippingPlanes[i],gCascadeNearAndFarClippingPlanes[i+1]);
                else
                    Helper_Ortho3D(pMatrixInv,cameraDistance,pMatrixFovyDeg,(float)w/(float)h,gCascadeNearAndFarClippingPlanes[i],gCascadeNearAndFarClippingPlanes[i+1]);
                Helper_InvertMatrix(pMatrixInv,pMatrixInv); // in-place operation (note tha we can't use Helper_InvertMatrixFast(...) here)
            }
        }
#       endif //USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE
    }


    if (w>0 && h>0 && !config.fullscreen_enabled) {
        // On exiting we'll like to save these data back
        config.windowed_width=w;
        config.windowed_height=h;
    }

    glViewport(0,0,w,h);    // This is what people often call in ResizeGL()

}


void InitGL(void) {

    // These are important, but often overlooked OpenGL calls
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_CULL_FACE);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);  // Otherwise transparent objects are not displayed correctly
    glClearColor(0.3f, 0.6f, 1.0f, 1.0f);
    glEnable(GL_TEXTURE_2D);    // Only needed for ffp, when VISUALIZE_DEPTH_TEXTURE is defined


	// ffp stuff
    glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);	
    glEnable(GL_COLOR_MATERIAL);
    glEnable(GL_NORMALIZE);

	// New
    InitShadowPass(&shadowPass);
    InitDefaultPass(&defaultPass);

    // Please note that after InitGL(), this implementation calls ResizeGL(...,...).
    // If you copy/paste this code you can call it explicitly...
}

void DestroyGL() {
	// New
    DestroyShadowPass(&shadowPass);
    DestroyDefaultPass(&defaultPass);
    // 40 display lists are generated by Helper_GlutDrawGeometry(...) if pgDisplayListBase!=0
    if (pgDisplayListBase && *pgDisplayListBase) {glDeleteLists(*pgDisplayListBase,40);*pgDisplayListBase=0;}
}


void DrawGL(void) 
{	
    // We need to calculate the "instantFrameTime", because it's necessary to "dynamic_resolution.h"
    static unsigned begin = 0;
    static unsigned cur_time = 0;
    unsigned elapsed_time,delta_time;

    static float vMatrixInverse[16];
    static float lvpMatrices[SHADOW_MAP_NUM_CASCADES*16];                 // = light_pMatrix*light_vMatrix
    static float biasedShadowMvpMatrices[SHADOW_MAP_NUM_CASCADES*16];     // multiplied per vMatrixInverse

    float elapsedMs;float cosAlpha,sinAlpha;    // used to move objects around

    int i;

    if (begin==0) begin = glutGet(GLUT_ELAPSED_TIME);
    elapsed_time = glutGet(GLUT_ELAPSED_TIME) - begin;
    delta_time = elapsed_time - cur_time;
    instantFrameTime = (float)delta_time*0.001f;
    cur_time = elapsed_time;

    elapsedMs = (float)elapsed_time;
    cosAlpha = cos(elapsedMs*0.0005f);
    sinAlpha = sin(elapsedMs*0.00075f);

    // view Matrix
    Helper_LookAt(vMatrix,cameraPos[0],cameraPos[1],cameraPos[2],targetPos[0],targetPos[1],targetPos[2],0,1,0);    
	glLoadMatrixf(vMatrix);
    glLightfv(GL_LIGHT0,GL_POSITION,lightDirection);    // Important: the ffp must recalculate internally lightDirectionEyeSpace based on vMatrix [=> every frame]

    // view Matrix inverse (it's the camera matrix). Used twice below. So it's better to keep it here.
    Helper_InvertMatrixFast(vMatrixInverse,vMatrix);


    // Draw to Shadow Map------------------------------------------------------------------------------------------
    {
#       ifndef USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE
        Helper_GetLightViewProjectionMatrices(lvpMatrices,gCascadeNearAndFarClippingPlanes,SHADOW_MAP_NUM_CASCADES,
                                              vMatrixInverse,
                                              pMatrixFovyDeg,current_aspect_ratio,config.use_camera_ortho3d_projection_matrix?cameraDistance:0, // Last arg is not present in the non-cascaded equivalent function (please read the Warning at the top of the file)
                                              lightDirection,1.0f/(float)SHADOW_MAP_HEIGHT
                                              //,0,0//,vMatrix
                                              );
#       else //USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE
        Helper_GetLightViewProjectionMatricesExtra(0,gCascadeNearAndFarClippingPlanes,SHADOW_MAP_NUM_CASCADES,
                                                   vMatrixInverse,
                                                   pMatrixFovyDeg,current_aspect_ratio,config.use_camera_ortho3d_projection_matrix?cameraDistance:0,
                                                   lightDirection,1.0f/(float)SHADOW_MAP_HEIGHT,
                                                   0,0,
                                                   gCascadePMatricesInv,    // Mandatory when we need to retrieve arguments that follow it
                                                   0,0,
                                                   lvpMatrices  // Technically this was provided as an 'lvpMatrices for optimal frustum culling usage' argument to be used in the 'Stable Shadow Mapping' case (but can be used to replace it too)
                                                   );
#       endif //USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE

        // Draw to shadow map texture
        glMatrixMode(GL_PROJECTION);glPushMatrix();glLoadIdentity();glMatrixMode(GL_MODELVIEW);        // We'll set the combined light view-projection matrix in GL_MODELVIEW (do you know that it's the same?)
        glBindFramebuffer(GL_FRAMEBUFFER, shadowPass.fbo);
        glViewport(0, 0, SHADOW_MAP_WIDTH,SHADOW_MAP_HEIGHT);
        glClear(GL_DEPTH_BUFFER_BIT);   // Clears all the shadow map
        glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
        glCullFace(GL_FRONT);
        glEnable(GL_DEPTH_CLAMP);
        glUseProgram(shadowPass.program);
        for (i=0;i<SHADOW_MAP_NUM_CASCADES;i++) {
            glViewport(SHADOW_MAP_HEIGHT*i, 0, SHADOW_MAP_HEIGHT,SHADOW_MAP_HEIGHT);
            glPushMatrix();glLoadMatrixf(&lvpMatrices[i*16]); // we load both (light) projection and view matrices here (it's the same after all)
            Helper_GlutDrawGeometry(elapsedMs,cosAlpha,sinAlpha,targetPos,pgDisplayListBase);  // Done SHADOW_MAP_NUM_CASCADES times!
            glPopMatrix();
        }
        glUseProgram(0);
        glDisable(GL_DEPTH_CLAMP);
        glCullFace(GL_BACK);
        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
        glBindFramebuffer(GL_FRAMEBUFFER,0);
        glMatrixMode(GL_PROJECTION);glPopMatrix();glMatrixMode(GL_MODELVIEW);

    }

    // Draw world
    {
        // biasedShadowMvpMatrix is used only in the DefaultPass:
        static float bias[16] = {0.5,0,0,0, 0,0.5,0,0,  0,0,0.5,0,    0.5,0.5,0.5,1}; // Moving from unit cube [-1,1] to [0,1]
        for (i=0;i<SHADOW_MAP_NUM_CASCADES;i++) {
            Helper_MultMatrix(&biasedShadowMvpMatrices[i*16],bias,&lvpMatrices[i*16]);
            Helper_MultMatrix(&biasedShadowMvpMatrices[i*16],&biasedShadowMvpMatrices[i*16],vMatrixInverse);  // We do this, so that when in the vs we multiply it with the camera mvMatrix, we get: biasedShadowMvpMatrix * mMatrix (using mMatrices directly in the shaders prevents the usage of double precision matrices: mvMatrices are good when converted to float to feed the shader, mMatrices are bad)
        }

        // Draw to world
        glViewport(0, 0, current_width,current_height);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glBindTexture(GL_TEXTURE_2D,shadowPass.textureId);
        glUseProgram(defaultPass.program);
        glUniformMatrix4fv(defaultPass.uniform_location_biasedShadowMvpMatrix, SHADOW_MAP_NUM_CASCADES /*setting many matrices*/, GL_FALSE /*transpose?*/,biasedShadowMvpMatrices);
        Helper_GlutDrawGeometry(elapsedMs,cosAlpha,sinAlpha,targetPos,pgDisplayListBase);
        glUseProgram(0);
        glBindTexture(GL_TEXTURE_2D,0);
    }



    if (config.show_fps && instantFrameTime>0) {
        if ((elapsed_time/1000)%2==0)   {
            printf("FPS=%1.0f\n",1.f/instantFrameTime);fflush(stdout);
            config.show_fps=0;
        }
    }


#   ifdef VISUALIZE_DEPTH_TEXTURE
    {
        glDisable(GL_DEPTH_TEST);
        glDisable(GL_CULL_FACE);
        glDepthMask(GL_FALSE);

        glMatrixMode(GL_PROJECTION);
        glPushMatrix();
        glLoadIdentity();

        glMatrixMode(GL_MODELVIEW);
        glPushMatrix();
        glLoadIdentity();
	
		glColor3f(1,1,1);
		glDisable(GL_LIGHTING);
        glEnable(GL_BLEND);
        glBindTexture(GL_TEXTURE_2D,shadowPass.textureId);
        glColor4f(1,1,1,0.9f);
        glBegin(GL_QUADS);
        glTexCoord2f(0,0);glVertex2f(-1,    0.75);
        glTexCoord2f(1,0);glVertex2f(-1+0.25*(float)SHADOW_MAP_NUM_CASCADES/current_aspect_ratio, 0.75);
        glTexCoord2f(1,1);glVertex2f(-1+0.25*(float)SHADOW_MAP_NUM_CASCADES/current_aspect_ratio, 1.0);
        glTexCoord2f(0,1);glVertex2f(-1,    1.0);
        glEnd();
        glBindTexture(GL_TEXTURE_2D,0);
        glDisable(GL_BLEND);
		glEnable(GL_LIGHTING);

        glPopMatrix();
        glMatrixMode(GL_PROJECTION);
        glPopMatrix();
        glMatrixMode(GL_MODELVIEW);

        glEnable(GL_DEPTH_TEST);
        glEnable(GL_CULL_FACE);
        glDepthMask(GL_TRUE);
    }
#   endif //VISUALIZE_DEPTH_TEXTURE


}

static void GlutDestroyWindow(void);
static void GlutCreateWindow();

void GlutCloseWindow(void)  {Config_Save(&config,ConfigFileName);}

void GlutNormalKeys(unsigned char key, int x, int y) {
    const int mod = glutGetModifiers();
    switch (key) {
    case 27: 	// esc key
        Config_Save(&config,ConfigFileName);
        GlutDestroyWindow();
#		ifdef __FREEGLUT_STD_H__
        glutLeaveMainLoop();
#		else
        exit(0);
#		endif
        break;
    case 13:	// return key
    {
        if (mod&GLUT_ACTIVE_CTRL) {
            config.fullscreen_enabled = gameModeWindowId ? 0 : 1;
            GlutDestroyWindow();
            GlutCreateWindow();
        }
    }
        break;
    }

}

static void updateCameraPos() {
    const float distanceY = sin(cameraPitch)*cameraDistance;
    const float distanceXZ = cos(cameraPitch)*cameraDistance;
    cameraPos[0] = targetPos[0] + sin(cameraYaw)*distanceXZ;
    cameraPos[1] = targetPos[1] + distanceY;
    cameraPos[2] = targetPos[2] + cos(cameraYaw)*distanceXZ;
}

static void updateDirectionalLight() {
    const float distanceY = sin(lightPitch);
    const float distanceXZ = cos(lightPitch);
    lightDirection[0] = sin(lightYaw)*distanceXZ;
    lightDirection[1] = distanceY;
    lightDirection[2] = cos(lightYaw)*distanceXZ;
    Helper_Vector3Normalize(lightDirection);
    lightDirection[3]=0.f;
}

static void resetCamera() {
    // You can set the initial camera position here through:
    targetPos[0]=0; targetPos[1]=0; targetPos[2]=0; // The camera target point
    cameraYaw = 2*M_PI;                             // The camera rotation around the Y axis
    cameraPitch = M_PI*0.125f;                      // The camera rotation around the XZ plane
    cameraDistance = 5;                             // The distance between the camera position and the camera target point

    updateCameraPos();
    if (config.use_camera_ortho3d_projection_matrix)    ResizeGL(current_width,current_height); // Needed because in Helper_Orho3D(...) cameraTargetDistance changes
}

static void resetLight() {
    lightYaw = M_PI*0.425f;
    lightPitch = M_PI*0.235f;
    updateDirectionalLight();
}

void GlutSpecialKeys(int key,int x,int y)
{
    const int mod = glutGetModifiers();
    if (!(mod&GLUT_ACTIVE_CTRL) && !(mod&GLUT_ACTIVE_SHIFT))	{
        switch (key) {
        case GLUT_KEY_LEFT:
        case GLUT_KEY_RIGHT:
            cameraYaw+= instantFrameTime*cameraSpeed*(key==GLUT_KEY_LEFT ? -4.0f : 4.0f);
            if (cameraYaw>M_PI) cameraYaw-=2*M_PI;
            else if (cameraYaw<=-M_PI) cameraYaw+=2*M_PI;
            updateCameraPos();		break;
        case GLUT_KEY_UP:
        case GLUT_KEY_DOWN:
            cameraPitch+= instantFrameTime*cameraSpeed*(key==GLUT_KEY_UP ? 2.f : -2.f);
            if (cameraPitch>M_PI-0.001f) cameraPitch=M_PI-0.001f;
            else if (cameraPitch<-M_PI*0.05f) cameraPitch=-M_PI*0.05f;
            updateCameraPos();
            break;
        case GLUT_KEY_PAGE_UP:
        case GLUT_KEY_PAGE_DOWN:
            cameraDistance+= instantFrameTime*cameraSpeed*(key==GLUT_KEY_PAGE_DOWN ? 25.0f : -25.0f);
            if (cameraDistance<1.f) cameraDistance=1.f;
            updateCameraPos();
            if (config.use_camera_ortho3d_projection_matrix)    ResizeGL(current_width,current_height); // Needed because in Helper_Orho3D(...) cameraTargetDistance changes
            break;
        case GLUT_KEY_F2:
            config.show_fps = !config.show_fps;
            //printf("showFPS: %s.\n",config.show_fps?"ON":"OFF");fflush(stdout);
            break;
        case GLUT_KEY_F1:
            config.use_camera_ortho3d_projection_matrix = !config.use_camera_ortho3d_projection_matrix;
            //printf("camera ortho mode: %s.\n",config.use_camera_ortho3d_projection_matrix?"ON":"OFF");fflush(stdout);
            ResizeGL(current_width,current_height);
            break;
        case GLUT_KEY_HOME:
            // Reset the camera
            resetCamera();
            break;
        }
    }
    else if (mod&GLUT_ACTIVE_CTRL) {
        switch (key) {
        case GLUT_KEY_LEFT:
        case GLUT_KEY_RIGHT:
        case GLUT_KEY_UP:
        case GLUT_KEY_DOWN:
        {
            // Here we move targetPos and cameraPos at the same time

            // We must find a pivot relative to the camera here (ignoring Y)
            float forward[3] = {targetPos[0]-cameraPos[0],0,targetPos[2]-cameraPos[2]};
            float up[3] = {0,1,0};
            float left[3];

            Helper_Vector3Normalize(forward);
            Helper_Vector3Cross(left,up,forward);
            {
                float delta[3] = {0,0,0};int i;
                if (key==GLUT_KEY_LEFT || key==GLUT_KEY_RIGHT) {
                    float amount = instantFrameTime*cameraSpeed*(key==GLUT_KEY_RIGHT ? -25.0f : 25.0f);
                    for (i=0;i<3;i++) delta[i]+=amount*left[i];
                }
                else {
                    float amount = instantFrameTime*cameraSpeed*(key==GLUT_KEY_DOWN ? -25.0f : 25.0f);
                    for ( i=0;i<3;i++) delta[i]+=amount*forward[i];
                }
                for ( i=0;i<3;i++) {
                    targetPos[i]+=delta[i];
                    cameraPos[i]+=delta[i];
                }
            }
        }
        break;
        case GLUT_KEY_PAGE_UP:
        case GLUT_KEY_PAGE_DOWN:
            // We use world space coords here.
            targetPos[1]+= instantFrameTime*cameraSpeed*(key==GLUT_KEY_PAGE_DOWN ? -25.0f : 25.0f);
            if (targetPos[1]<-50.f) targetPos[1]=-50.f;
            else if (targetPos[1]>500.f) targetPos[1]=500.f;
            updateCameraPos();
            if (config.use_camera_ortho3d_projection_matrix)    ResizeGL(current_width,current_height); // Needed because in Helper_Orho3D(...) cameraTargetDistance changes
        break;
        }
    }
    else if (mod&GLUT_ACTIVE_SHIFT)	{
        switch (key) {
        case GLUT_KEY_LEFT:
        case GLUT_KEY_RIGHT:
            lightYaw+= instantFrameTime*cameraSpeed*(key==GLUT_KEY_LEFT ? -4.0f : 4.0f);
            if (lightYaw>M_PI) lightYaw-=2*M_PI;
            else if (lightYaw<=-M_PI) lightYaw+=2*M_PI;
            updateDirectionalLight();
            break;
        case GLUT_KEY_UP:
        case GLUT_KEY_DOWN:
        case GLUT_KEY_PAGE_UP:
        case GLUT_KEY_PAGE_DOWN:
            lightPitch+= instantFrameTime*cameraSpeed*( (key==GLUT_KEY_UP || key==GLUT_KEY_PAGE_UP) ? 2.f : -2.f);
            if (lightPitch>M_PI-0.001f) lightPitch=M_PI-0.001f;
            else if (lightPitch<-M_PI*0.05f) lightPitch=-M_PI*0.05f;
            updateDirectionalLight();
            break;
        case GLUT_KEY_HOME:
            // Reset the light
            resetLight();
            break;
        }
    }
}

void GlutMouse(int a,int b,int c,int d) {

}

// Note that we have used GlutFakeDrawGL() so that at startup
// the calling order is: InitGL(),ResizeGL(...),DrawGL()
// Also note that glutSwapBuffers() must NOT be called inside DrawGL()
static void GlutDrawGL(void)		{DrawGL();glutSwapBuffers();}
static void GlutIdle(void)			{glutPostRedisplay();}
static void GlutFakeDrawGL(void) 	{glutDisplayFunc(GlutDrawGL);}
void GlutDestroyWindow(void) {
    if (gameModeWindowId || windowId)	{
        DestroyGL();

        if (gameModeWindowId) {
            glutLeaveGameMode();
            gameModeWindowId = 0;
        }
        if (windowId) {
            glutDestroyWindow(windowId);
            windowId=0;
        }
    }
}
void GlutCreateWindow() {
    GlutDestroyWindow();
    if (config.fullscreen_enabled)	{
        char gms[16]="";
        if (config.fullscreen_width>0 && config.fullscreen_height>0)	{
            sprintf(gms,"%dx%d:32",config.fullscreen_width,config.fullscreen_height);
            glutGameModeString(gms);
            if (glutGameModeGet (GLUT_GAME_MODE_POSSIBLE)) gameModeWindowId = glutEnterGameMode();
            else config.fullscreen_width=config.fullscreen_height=0;
        }
        if (gameModeWindowId==0)	{
            const int screenWidth = glutGet(GLUT_SCREEN_WIDTH);
            const int screenHeight = glutGet(GLUT_SCREEN_HEIGHT);
            sprintf(gms,"%dx%d:32",screenWidth,screenHeight);
            glutGameModeString(gms);
            if (glutGameModeGet (GLUT_GAME_MODE_POSSIBLE)) gameModeWindowId = glutEnterGameMode();
        }
    }
    if (!gameModeWindowId) {
        char windowTitle[1024] = PROGRAM_NAME".c\t";
#       ifdef  USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE
        strcat(windowTitle,"[Unstable]\t");
#       endif  //USE_UNSTABLE_SHADOW_MAPPING_TECHNIQUE
        strcat(windowTitle,"("XSTR_MACRO(SHADOW_MAP_HEIGHT)"x"SHADOW_MAP_NUM_CASCADES_STRING")");
        config.fullscreen_enabled = 0;
        glutInitWindowPosition(100,100);
        glutInitWindowSize(config.windowed_width,config.windowed_height);
        windowId = glutCreateWindow(windowTitle);
    }

    glutKeyboardFunc(GlutNormalKeys);
    glutSpecialFunc(GlutSpecialKeys);
    glutMouseFunc(GlutMouse);
    glutIdleFunc(GlutIdle);
    glutReshapeFunc(ResizeGL);
    glutDisplayFunc(GlutFakeDrawGL);
#   ifdef __FREEGLUT_STD_H__
    glutWMCloseFunc(GlutCloseWindow);
#   endif //__FREEGLUT_STD_H__

#ifdef USE_GLEW
    {
        GLenum err = glewInit();
        if( GLEW_OK != err ) {
            fprintf(stderr, "Error initializing GLEW: %s\n", glewGetErrorString(err) );
            return;
        }
    }
#endif //USE_GLEW

    InitGL();

}


int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
    //glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
#ifdef __FREEGLUT_STD_H__
    glutSetOption ( GLUT_ACTION_ON_WINDOW_CLOSE, GLUT_ACTION_CONTINUE_EXECUTION ) ;
#endif //__FREEGLUT_STD_H__

    Config_Init(&config);
    Config_Load(&config,ConfigFileName);

    GlutCreateWindow();

    //OpenGL info
    printf("\nGL Vendor: %s\n", glGetString( GL_VENDOR ));
    printf("GL Renderer : %s\n", glGetString( GL_RENDERER ));
    printf("GL Version (string) : %s\n",  glGetString( GL_VERSION ));
    printf("GLSL Version : %s\n", glGetString( GL_SHADING_LANGUAGE_VERSION ));
    //printf("GL Extensions:\n%s\n",(char *) glGetString(GL_EXTENSIONS));
    {int maxTextureSize=0;glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxTextureSize);printf("Max Texture Size: %d\n", maxTextureSize);}
    // Many GPUs return 16384 as their max size.
    // For 4 bytes per pixel: 16384*16384*4 bytes = 1 Gb
    // For 4 float per pixel: 16384*16384*4 floats (a floating point texture) = 4Gb.
    // Many GPUs don't even have 4Gb of memory

    printf("\nKEYS:\n");
    printf("AROW KEYS + PAGE_UP/PAGE_DOWN:\tmove camera (optionally with CTRL down)\n");
    printf("HOME KEY:\t\t\treset camera\n");
    printf("ARROW KEYS + SHIFT:\tmove directional light\n");
    printf("CTRL+RETURN:\t\ttoggle fullscreen on/off\n");
    printf("F2:\t\t\tdisplay FPS\n");
    printf("F1:\t\t\ttoggle camera ortho mode on and off\n");
    printf("\n");

    resetCamera();  // Mandatory
    resetLight();   // Mandatory

    glutMainLoop();


    return 0;
}