Added libm, PortView, Triangles, Orthographics View

Added libm into build system '-lm'.
Edited shaders.
Added dynamic resize window.
Added another triangle and test depth with intersection triangles.

Makefile

@@ -1,6 +1,6 @@
 CC=gcc
 CFLAGS=-O1 -DDEBUG -g -ggdb -std=c23
-LIBS=`pkg-config sdl3 --cflags --libs` -lGL -lGLEW
+LIBS=`pkg-config sdl3 --cflags --libs` -lGL -lGLEW -lm
 
 OBJ = main.o
 

fragment.glsl

@@ -1,8 +1,9 @@
-#version 460
+#version 330
 
-out vec4 outputColor;
+smooth in vec4 _colour;
 
+out vec4 outputColour;
 void main()
 {
-    outputColor = vec4(1.0f, 0.0f, 0.0f, 1.0f);
+    outputColour = _colour;
 }

main.c

@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 
 #include <GL/glew.h>
 #include <SDL3/SDL.h>
@@ -29,10 +30,15 @@ static double GetTime( void )
 static void SetTitle ( SDL_Window *window )
 {
     char title[48] = {0};
-    SDL_snprintf(title, sizeof(title), "Hello Triangle! Framelimit: %6.3f Hz", FPS);
+    SDL_snprintf(title, sizeof(title), "Hello Triangles! Framelimit: %6.3f Hz", FPS);
     SDL_SetWindowTitle(window, title);
 }
 
+void resizeWindow ( int width, int height )
+{
+    glViewport(0, 0, (GLsizei)width, (GLsizei)height);
+}
+
 void panicError ( void )
 {
     SDL_GL_DestroyContext(glcontext);
@@ -131,7 +137,7 @@ void createProgram ( GLuint *shaders, int len )
         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLen);
         GLchar *info = SDL_malloc(sizeof(GLchar) * (infoLen + 1));
         glGetProgramInfoLog(program, infoLen, NULL, info);
-        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "Link failed: %s.", info);
+        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "Link failed: %s", info);
         panicError();
     }
 }
@@ -139,15 +145,33 @@ void createProgram ( GLuint *shaders, int len )
 void createBuffer ( void )
 {
     float vertices[] = {
-        -1.0f, -1.0f, 0.0f,
+      -1.0f, -1.0f,  1.0f, 1.0f, // left-bottom
-        1.0f, -1.0f, 0.0f,
+       1.0f, -1.0f,  1.0f, 1.0f, // right-bottom
-        0.0f, 1.0f, 0.0f
+       0.0f,  1.0f, -1.0f, 1.0f, // top
+
+      -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
     };
     glGenBuffers(1, &vbo);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 }
 
+void setUniformLocation ( void )
+{
+    /* offsetLoc = glGetUniformLocation(program, "_offset"); */
+}
+
 void startShaderProg ( void )
 {
     createBuffer();
@@ -161,19 +185,29 @@ void startShaderProg ( void )
     for (int i = 0; i < len; i++) {
         glDeleteShader(shaders[i]);
     }
+
+    setUniformLocation();
+    glEnable(GL_DEPTH_TEST);
+    glDepthMask(GL_TRUE);
+    glDepthFunc(GL_LEQUAL);
+    glDepthRange(0.0f, 1.0f);
 }
 
 void _GLBuffer( void )
 {
     glClearColor(0.0f, 0.0f, 1.0f, 0.0f);
-    glClear(GL_COLOR_BUFFER_BIT);
+    glClearDepth(1.0f);
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
     glUseProgram(program);
 
     glEnableVertexAttribArray(0);
+    glEnableVertexAttribArray(1);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
+    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
-    glDrawArrays(GL_TRIANGLES, 0, 3);
+    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, (void *) (6*4*sizeof(float)));
+    glDrawArrays(GL_TRIANGLES, 0, 6);
     glDisableVertexAttribArray(0);
+    glDisableVertexAttribArray(1);
 
     glUseProgram(0);
 }
@@ -183,36 +217,44 @@ int main( int argc, char* argv[] )
     const int WIDTH = 640;
     const int HEIGHT = 480;
     int delay_threshold = 2;
-    int r, g, b, GLJ, GLN = 0;
+    int r, g, b, alpha_s, depth_s, stencil_s, dbuffer, GLJ, GLN, GLAccel, GLP = 0;
     double sleep_time = 0;
     double time_counter = 0;
     bool loopShouldStop = false;
 
     SDL_SetHint(SDL_HINT_RENDER_VSYNC, 0);
     if (!SDL_Init(SDL_INIT_VIDEO)) {
-        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_Init failed: %s.", SDL_GetError());
+        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_Init failed: %s", SDL_GetError());
+        panicError();
     }
 
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
+    if (!SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE)) {
+        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "Set atrribute SDL_GL_CONTEXT_PROFILE_MASK: %s", SDL_GetError());
+        panicError();
+    }
+
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
-    SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5);
+    SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
-    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5);
+    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
-    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5);
+    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
-    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
+    SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
+    SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
 
     PerformancePeriod = 1.0 / SDL_GetPerformanceFrequency();
     time_counter = GetTime();
 
-    window = SDL_CreateWindow("Hello SDL", WIDTH, HEIGHT, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
+    window = SDL_CreateWindow("Hello SDL", WIDTH, HEIGHT, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
     if (!window) {
-        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_CreateWindow: %s.", SDL_GetError());
+        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_CreateWindow: %s", SDL_GetError());
         panicError();
     }
 
     glcontext = SDL_GL_CreateContext(window);
     if (!glcontext) {
-        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_GL_CreateContext: %s.", SDL_GetError());
+        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_GL_CreateContext: %s", SDL_GetError());
         panicError();
     }
 
@@ -223,20 +265,27 @@ int main( int argc, char* argv[] )
     glewExperimental = GL_TRUE;
     GLenum err = glewInit();
     if (err != GLEW_OK) {
-        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "glewInit: %s.", glewGetErrorString(err));
+        SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "glewInit: %s", glewGetErrorString(err));
         panicError();
     }
 
     SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "Status: Using GLEW %s\n", glewGetString(GLEW_VERSION));
-    err = SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &GLJ);
+    SDL_GL_GetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, &GLP);
+    SDL_GL_GetAttribute(SDL_GL_ACCELERATED_VISUAL, &GLAccel);
+    SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &GLJ);
     SDL_GL_GetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, &GLN);
     SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &r);
     SDL_GL_GetAttribute(SDL_GL_GREEN_SIZE, &g);
     SDL_GL_GetAttribute(SDL_GL_BLUE_SIZE, &b);
+    SDL_GL_GetAttribute(SDL_GL_ALPHA_SIZE, &alpha_s);
+    SDL_GL_GetAttribute(SDL_GL_DEPTH_SIZE, &depth_s);
+    SDL_GL_GetAttribute(SDL_GL_STENCIL_SIZE, &stencil_s);
+    SDL_GL_GetAttribute(SDL_GL_DOUBLEBUFFER, &dbuffer);
 
-    SDL_Log("%s", SDL_GetError());
+    SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "OpenGL Versin: %d.%d, OpenGL Accelerated: %d, OpenGL Profile Mask: %d",
-
+                   GLJ, GLN, GLAccel, GLP);
-    SDL_LogVerbose(SDL_LOG_CATEGORY_RENDER, "Red size: %d, Green size: %d, Blue size: %d, OpenGL: %d.%d.", r, g, b, GLJ, GLN);
+    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);
 
     SDL_GL_SetSwapInterval(0);
     startShaderProg();
@@ -247,6 +296,9 @@ int main( int argc, char* argv[] )
         while (SDL_PollEvent(&e)) {
             if (e.type == SDL_EVENT_QUIT)
                 loopShouldStop = true;
+            else if (e.type == SDL_EVENT_WINDOW_RESIZED) {
+                resizeWindow(e.window.data1, e.window.data2);
+            }
             else if (e.type == SDL_EVENT_KEY_DOWN) {
                 if (e.key.key == SDLK_X) {
                     FPS -= 0.1;
@@ -255,8 +307,7 @@ int main( int argc, char* argv[] )
                     }
                     FrameTime = 1.0 / FPS;
                     SetTitle(window);
-                }
+                } else if (e.key.key == SDLK_C) {
-                else if (e.key.key == SDLK_C) {
                     FPS += 0.1;
                     FrameTime = 1.0 / FPS;
                     SetTitle(window);
@@ -268,7 +319,7 @@ int main( int argc, char* argv[] )
 
         _GLBuffer();
         if (!SDL_GL_SwapWindow(window)) {
-            SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_GL_SwapWwindow: %s.", SDL_GetError());
+            SDL_LogCritical(SDL_LOG_CATEGORY_ASSERT, "SDL_GL_SwapWwindow: %s", SDL_GetError());
             panicError();
         }
 
@@ -278,7 +329,7 @@ int main( int argc, char* argv[] )
             SDL_Delay(ms);
             if (time_counter < GetTime()) {
                 delay_threshold++;
-                SDL_Log("Slept too long. Increased threshold to %u ms.", delay_threshold);
+                SDL_Log("Slept too long. Increased threshold to %u ms", delay_threshold);
             }
         }
 

vertex.glsl

@@ -1,8 +1,12 @@
-#version 460
+#version 330
 
-layout(location = 0) in vec3 pos;
+layout(location = 0) in vec4 pos;
+layout(location = 1) in vec4 colour;
+
+smooth out vec4 _colour;
 
 void main()
 {
-    gl_Position = vec4(pos.x, pos.y, pos.z, 1.0);
+    gl_Position = pos;
+    _colour = colour;
 }