Start improving opengl 3 examples

Author: cirosantilli

opengl/README.md

@@ -49,7 +49,8 @@
         1.  [IBO](glfw_ibo.c)
         1.  [transform](glfw_transform.c)
         1.  [gl_FragCoord](glfw_gl_frag_coord.c)
-        1.  [heatplot](heatplot.c)
+        1.  [heatmap](glfw_heatmap.c)
+        1.  [Texture](glfw_texture.c)
         1.  Naughty
             1.  [Infinite loop shader](glfw_infinite_loop_shader.c.off)
             1.  [Memory overflow shader](glfw_memory_overflow_shader.c.off)

opengl/TODO.md

@@ -34,14 +34,13 @@
     - http://stackoverflow.com/questions/5734794/mouse-movement-opengl
     - http://stackoverflow.com/questions/1426415/opengl-moving-camera-with-mouse
     - http://gamedev.stackexchange.com/questions/53333/how-to-implement-a-basic-arcball-camera-in-opengl-with-glm
--   VAO, VBO http://stackoverflow.com/questions/11821336/what-are-vertex-array-objects
-    -   Immediate mode vs retained mode:
-        - https://en.wikipedia.org/wiki/Retained_mode
-        - https://en.wikipedia.org/wiki/Immediate_mode_(computer_graphics)
-        - immediate mode is deprecated. So like, glBegin, glEnd and glVertex which we use in every test program are deprecated. Lol.
-        - http://gamedev.stackexchange.com/questions/21733/why-does-opengl-3-only-allow-vbos
-        - http://stackoverflow.com/questions/6733934/what-does-immediate-mode-mean-in-opengl Hello world requested but not provided, too long, lol. Opportunity!
-        - http://gamedev.stackexchange.com/questions/21733/why-does-opengl-3-only-allow-vbos
+-   Immediate mode vs retained mode:
+    - https://en.wikipedia.org/wiki/Retained_mode
+    - https://en.wikipedia.org/wiki/Immediate_mode_(computer_graphics)
+    - immediate mode is deprecated. So like, glBegin, glEnd and glVertex which we use in every test program are deprecated. Lol.
+    - http://gamedev.stackexchange.com/questions/21733/why-does-opengl-3-only-allow-vbos
+    - http://stackoverflow.com/questions/6733934/what-does-immediate-mode-mean-in-opengl Hello world requested but not provided, too long, lol. Opportunity!
+    - http://gamedev.stackexchange.com/questions/21733/why-does-opengl-3-only-allow-vbos
 -   https://en.wikipedia.org/wiki/Stencil_buffer
     - http://www.learnopengl.com/#!Advanced-OpenGL/Stencil-testing
 -   shading, glsl

opengl/bibliography.md

@@ -62,6 +62,7 @@ Demos:
 
 - <https://github.com/prideout/recipes>
 - <https://www.youtube.com/watch?v=H-3yPXXZUC8>
+- <https://github.com/premsasidharan/gpu_img_proc/tree/master/test/edge_camera> <https://www.youtube.com/watch?v=fJtOdJ9MHsA> GLSL Linux camera real time edge detection shown on screen. Getting started: <https://github.com/premsasidharan/gpu_img_proc/issues/1#issuecomment-257504913>
 
 Unevaluated:
 

opengl/common.h

@@ -35,12 +35,14 @@ static void common_fps_print() {
     }
 }
 
-/* Build and compile shader program, return it's ID. */
+/* Build and compile shader program, return its ID. */
 GLint common_get_shader_program(
-        const char *vertex_shader_source,
-        const char *fragment_shader_source) {
+    const char *vertex_shader_source,
+    const char *fragment_shader_source
+) {
     GLchar *log = NULL;
-    GLint fragment_shader, log_length, program, success, vertex_shader;
+    GLint log_length, success;
+    GLuint fragment_shader, program, vertex_shader;
 
     /* Vertex shader */
     vertex_shader = glCreateShader(GL_VERTEX_SHADER);

opengl/glfw_color_array.c

@@ -6,33 +6,26 @@ Color interpolation on the fragment shader is automatic.
 http://stackoverflow.com/questions/6733934/what-does-immediate-mode-mean-in-opengl
 */
 
-#include <stdio.h>
-#include <stdlib.h>
-
-#define GLEW_STATIC
-#include <GL/glew.h>
-#include <GLFW/glfw3.h>
-
 #include "common.h"
 
-static const GLuint WIDTH = 800;
-static const GLuint HEIGHT = 600;
-/* ourColor is passed on to the fragment shader. */
+static const GLuint WIDTH = 500;
+static const GLuint HEIGHT = 500;
+/* fragColor is passed on to the fragment shader. */
 static const GLchar *vertex_shader_source =
     "#version 330 core\n"
-    "layout (location = 0) in vec3 position;\n"
-    "layout (location = 1) in vec3 color;\n"
-    "out vec3 ourColor;\n"
+    "in vec3 position;\n"
+    "in vec3 vertColor;\n"
+    "out vec3 fragColor;\n"
     "void main() {\n"
     "    gl_Position = vec4(position, 1.0f);\n"
-    "    ourColor = color;\n"
+    "    fragColor = vertColor;\n"
     "}\n";
 static const GLchar *fragment_shader_source =
     "#version 330 core\n"
-    "in vec3 ourColor;\n"
+    "in vec3 fragColor;\n"
     "out vec4 color;\n"
     "void main() {\n"
-    "    color = vec4(ourColor, 1.0f);\n"
+    "    color = vec4(fragColor, 1.0f);\n"
     "}\n";
 static GLfloat vertices[] = {
 /*   Positions          Colors */
@@ -42,43 +35,66 @@ static GLfloat vertices[] = {
 };
 
 int main(void) {
-    GLint shader_program;
+    GLFWwindow *window;
+    GLuint attribute_vertColor, attribute_position, program, vbo, vao;
 
+    /* Window system. */
     glfwInit();
-    GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, __FILE__, NULL, NULL);
+    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
+    window = glfwCreateWindow(WIDTH, HEIGHT, __FILE__, NULL, NULL);
     glfwMakeContextCurrent(window);
-    glewExperimental = GL_TRUE;
     glewInit();
-    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
-    glViewport(0, 0, WIDTH, HEIGHT);
 
-    shader_program = common_get_shader_program(vertex_shader_source, fragment_shader_source);
+    /* Shader setup. */
+    program = common_get_shader_program(vertex_shader_source, fragment_shader_source);
+    attribute_position = glGetAttribLocation(program, "position");
+    attribute_vertColor = glGetAttribLocation(program, "vertColor");
 
-    GLuint vbo, vao;
+    /* Buffer setup. */
     glGenVertexArrays(1, &vao);
     glGenBuffers(1, &vbo);
     glBindVertexArray(vao);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
-    /* Position attribute */
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
-    glEnableVertexAttribArray(0);
-    /* Color attribute */
-    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
-    glEnableVertexAttribArray(1);
+    glVertexAttribPointer(
+        attribute_position,
+        3,
+        GL_FLOAT,
+        GL_FALSE,
+        6 * sizeof(GLfloat),
+        (GLvoid*)0
+    );
+    glEnableVertexAttribArray(attribute_position);
+    glVertexAttribPointer(
+        attribute_vertColor,
+        3,
+        GL_FLOAT,
+        GL_FALSE,
+        6 * sizeof(GLfloat),
+        (GLvoid*)(3 * sizeof(GLfloat))
+    );
+    glEnableVertexAttribArray(attribute_vertColor);
+    glBindVertexArray(0);
+
+    /* Draw. */
+    glViewport(0, 0, WIDTH, HEIGHT);
+    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT);
+    glUseProgram(program);
+    glBindVertexArray(vao);
+    glDrawArrays(GL_TRIANGLES, 0, 3);
     glBindVertexArray(0);
+    glfwSwapBuffers(window);
 
+    /* Main loop. */
     while (!glfwWindowShouldClose(window)) {
         glfwPollEvents();
-        glClear(GL_COLOR_BUFFER_BIT);
-        glUseProgram(shader_program);
-        glBindVertexArray(vao);
-        glDrawArrays(GL_TRIANGLES, 0, 3);
-        glBindVertexArray(0);
-        glfwSwapBuffers(window);
     }
+
+    /* Cleanup. */
     glDeleteVertexArrays(1, &vao);
     glDeleteBuffers(1, &vbo);
+    glDeleteProgram(program);
     glfwTerminate();
     return EXIT_SUCCESS;
 }

opengl/glfw_heatmap.c

@@ -57,43 +57,46 @@ int main(void) {
         pi2 = 2.0 * acos(-1.0)
     ;
 
+    /* Window system. */
     glfwInit();
     window = glfwCreateWindow(WIDTH, HEIGHT, __FILE__, NULL, NULL);
     glfwMakeContextCurrent(window);
     glewInit();
 
+    /* Shader setup. */
     program = common_get_shader_program(vertex_shader_source, fragment_shader_source);
     attribute_coord2d = glGetAttribLocation(program, attribute_name);
-    if (attribute_coord2d == -1) {
-        fprintf(stderr, "error: attribute_coord2d: %s\n", attribute_name);
-        return EXIT_FAILURE;
-    }
     height_location = glGetUniformLocation(program, "height");
     periods_x_location = glGetUniformLocation(program, "periods_x");
     periods_y_location = glGetUniformLocation(program, "periods_y");
     pi2_location = glGetUniformLocation(program, "pi2");
     time_location = glGetUniformLocation(program, "time");
     width_location = glGetUniformLocation(program, "width");
 
+    /* Global settings. */
     glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
     glUseProgram(program);
     glViewport(0, 0, WIDTH, HEIGHT);
 
+    /* vbo */
     glGenBuffers(1, &vbo);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
+    /* ibo */
     glGenBuffers(1, &ibo);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
     glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indexes), indexes, GL_STATIC_DRAW);
     glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &ibo_size);
 
+    /* Uniforms. */
     glUniform1f(pi2_location, pi2);
     glUniform1f(width_location, WIDTH);
     glUniform1f(height_location, HEIGHT);
     glUniform1f(periods_x_location, periods_x);
     glUniform1f(periods_y_location, periods_y);
 
+    /* Main loop. */
     common_fps_init();
     while (!glfwWindowShouldClose(window)) {
         glfwPollEvents();
@@ -116,6 +119,7 @@ int main(void) {
         common_fps_print();
     }
 
+    /* Cleanup. */
     glDeleteBuffers(1, &ibo);
     glDeleteBuffers(1, &vbo);
     glDeleteProgram(program);