Furtrum and quad.

main.c

@@ -14,6 +14,8 @@ SDL_GLContext glcontext = NULL;
 
 GLuint program;
 GLuint vbo;
+GLuint ibo;
+GLuint projMatrLoc;
 
 static double FPS = INITIAL_FPS;
 static double FrameTime = 1.0 / INITIAL_FPS;
@@ -34,8 +36,32 @@ static void SetTitle ( SDL_Window *window )
     SDL_SetWindowTitle(window, title);
 }
 
+float toRad ( float deg )
+{
+    /* 180 deg = pi */
+    /* "deg" deg = x */
+    return deg * 3.141593f / 180.0f;
+}
+
 void resizeWindow ( int width, int height )
 {
+    float n = 1.0f; // near
+    float f = 3.0f; // far
+    float fov = toRad(90); // 90 or 65 for console
+    float aspect = width / (float) height;
+    float t = n * tanf (fov / 2.0f);
+    float r = t * aspect;
+
+    float projMatr[] = {
+        n/r, 0,   0,              0,
+        0,   n/t, 0,              0,
+        0,   0,   (f+n)/(n-f),    -1,
+        0,   0,   2.0f*n*f/(n-f), 0
+    }; // it's not rows, it's columns, 'GL_FALSE'
+    SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "n=%.1f f=%.1f fov=%.2f aspect=%.2f t=%.2f r=%.2f\n", n, f, fov, aspect, t, r);
+    glUseProgram(program);
+    glUniformMatrix4fv(projMatrLoc, 1, GL_FALSE, projMatr);
+    glUseProgram(0);
     glViewport(0, 0, (GLsizei)width, (GLsizei)height);
 }
 
@@ -144,32 +170,36 @@ void createProgram ( GLuint *shaders, int len )
 
 void createBuffer ( void )
 {
+    GLushort indices[] = {
+        0, 1, 2,
+        0, 2, 3
+    };
     float vertices[] = {
-      -1.0f, -1.0f,  1.0f, 1.0f, // left-bottom
+      -1.0f, -1.0f, -2.0f, 1.0f, // left-bottom
-       1.0f, -1.0f,  1.0f, 1.0f, // right-bottom
+      -1.0f,  1.0f, -2.0f, 1.0f, // left-top
-       0.0f,  1.0f, -1.0f, 1.0f, // top
+       1.0f,  1.0f, -2.0f, 1.0f, // right-top
-
+       1.0f, -1.0f, -2.0f, 1.0f, // right-bottom
-      -1.0f,  1.0f,  1.0f, 1.0f, // left-top
-       1.0f,  1.0f,  1.0f, 1.0f, // right-top
-       0.0f, -1.0f, -1.0f, 1.0f, // bottom
 
        // colours
        1.0f, 0.0f, 0.0f, 1.0f, // red
        0.0f, 1.0f, 0.0f, 1.0f, // green
-       0.0f, 0.0f, 1.0f, 1.0f, // blue
-
-       1.0f, 1.0f, 0.0f, 1.0f, // yellow
        1.0f, 0.0f, 1.0f, 1.0f, // purple
-       0.0f, 1.0f, 1.1f, 1.0f  // aqua
+       1.0f, 1.0f, 0.0f, 1.0f  // yellow
     };
     glGenBuffers(1, &vbo);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+
+    glGenBuffers(1, &ibo);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 }
 
 void setUniformLocation ( void )
 {
-    /* offsetLoc = glGetUniformLocation(program, "_offset"); */
+    projMatrLoc = glGetUniformLocation(program, "projMatr");
 }
 
 void startShaderProg ( void )
@@ -203,9 +233,10 @@ void _GLBuffer( void )
     glEnableVertexAttribArray(0);
     glEnableVertexAttribArray(1);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
     glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
-    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, (void *) (6*4*sizeof(float)));
+    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, (void *) (4*4*sizeof(float)));
-    glDrawArrays(GL_TRIANGLES, 0, 6);
+    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, 0);
     glDisableVertexAttribArray(0);
     glDisableVertexAttribArray(1);
 
@@ -216,10 +247,10 @@ int main( int argc, char* argv[] )
 {
     const int WIDTH = 640;
     const int HEIGHT = 480;
-    int delay_threshold = 2;
+    int delayThreshold = 2;
-    int r, g, b, alpha_s, depth_s, stencil_s, dbuffer, GLJ, GLN, GLAccel, GLP = 0;
+    int r, g, b, alpha_s, depth_s, stencil_s, dbuffer, glVersionMa, glVersionMi, glAccel, glProfile = 0;
-    double sleep_time = 0;
+    double sleepTime = 0;
-    double time_counter = 0;
+    double timeCounter = 0;
     bool loopShouldStop = false;
 
     SDL_SetHint(SDL_HINT_RENDER_VSYNC, 0);
@@ -244,7 +275,7 @@ int main( int argc, char* argv[] )
     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
 
     PerformancePeriod = 1.0 / SDL_GetPerformanceFrequency();
-    time_counter = GetTime();
+    timeCounter = GetTime();
 
     window = SDL_CreateWindow("Hello SDL", WIDTH, HEIGHT, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
     if (!window) {
@@ -270,10 +301,10 @@ int main( int argc, char* argv[] )
     }
 
     SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "Status: Using GLEW %s\n", glewGetString(GLEW_VERSION));
-    SDL_GL_GetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, &GLP);
+    SDL_GL_GetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, &glProfile);
-    SDL_GL_GetAttribute(SDL_GL_ACCELERATED_VISUAL, &GLAccel);
+    SDL_GL_GetAttribute(SDL_GL_ACCELERATED_VISUAL, &glAccel);
-    SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &GLJ);
+    SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &glVersionMa);
-    SDL_GL_GetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, &GLN);
+    SDL_GL_GetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, &glVersionMi);
     SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &r);
     SDL_GL_GetAttribute(SDL_GL_GREEN_SIZE, &g);
     SDL_GL_GetAttribute(SDL_GL_BLUE_SIZE, &b);
@@ -282,8 +313,8 @@ int main( int argc, char* argv[] )
     SDL_GL_GetAttribute(SDL_GL_STENCIL_SIZE, &stencil_s);
     SDL_GL_GetAttribute(SDL_GL_DOUBLEBUFFER, &dbuffer);
 
-    SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "OpenGL Versin: %d.%d, OpenGL Accelerated: %d, OpenGL Profile Mask: %d",
+    SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "OpenGL Version: %d.%d, OpenGL Accelerated: %d, OpenGL Profile Mask: %d",
-                   GLJ, GLN, GLAccel, GLP);
+                   glVersionMa, glVersionMi, glAccel, glProfile);
     SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "Red size: %d, Green size: %d, Blue size: %d, Alpha size: %d, Depth size: %d, Stencil size: %d, DoubleBuffer: %d",
                    r, g, b, alpha_s, depth_s, stencil_s, dbuffer);
 
@@ -323,20 +354,20 @@ int main( int argc, char* argv[] )
             panicError();
         }
 
-        sleep_time = time_counter - GetTime();
+        sleepTime = timeCounter - GetTime();
-        if (sleep_time * 1000 > delay_threshold) {
+        if (sleepTime * 1000 > delayThreshold) {
-            Uint32 ms = (Uint32)(sleep_time * 1000) - delay_threshold;
+            Uint32 ms = (Uint32)(sleepTime * 1000) - delayThreshold;
             SDL_Delay(ms);
-            if (time_counter < GetTime()) {
+            if (timeCounter < GetTime()) {
-                delay_threshold++;
+                delayThreshold++;
-                SDL_Log("Slept too long. Increased threshold to %u ms", delay_threshold);
+                SDL_Log("Slept too long. Increased threshold to %u ms", delayThreshold);
             }
         }
 
-        while (time_counter > GetTime()) {
+        while (timeCounter > GetTime()) {
         /* Waiting for the right moment. */
         }
-        time_counter += FrameTime;
+        timeCounter += FrameTime;
     }
 
     SDL_DestroyWindow(window);

vertex.glsl

@@ -3,10 +3,12 @@
 layout(location = 0) in vec4 pos;
 layout(location = 1) in vec4 colour;
 
+uniform mat4 projMatr;
+
 smooth out vec4 _colour;
 
 void main()
 {
-    gl_Position = pos;
+    gl_Position = projMatr * pos;
     _colour = colour;
 }