Ex 3,4,5,6 documentation

Author: bassel97

README.md

@@ -13,10 +13,10 @@ This repository contains examples of how to use OpenGL with C++17. It is made fo
 | ---- | ----------- | ------ |
 | Empty Window | [ex01_empty_window.cpp](source/examples/ex01_empty_window.cpp) | :white_check_mark: |
 | Shader Introduction | [ex02_shader_introduction.cpp](source/examples/ex02_shader_introduction.cpp) | :white_check_mark: |
-| Uniforms | [ex03_uniforms.cpp](source/examples/ex03_uniforms.cpp) |  |
-| Varyings | [ex04_varyings.cpp](source/examples/ex04_varyings.cpp) |  |
-| Attributes | [ex05_attributes.cpp](source/examples/ex05_attributes.cpp) |  |
-| Multiple Attributes | [ex06_multiple_attributes.cpp](source/examples/ex06_multiple_attributes.cpp) |  |
+| Uniforms | [ex03_uniforms.cpp](source/examples/ex03_uniforms.cpp) | :white_check_mark: |
+| Varyings | [ex04_varyings.cpp](source/examples/ex04_varyings.cpp) | :white_check_mark: |
+| Attributes | [ex05_attributes.cpp](source/examples/ex05_attributes.cpp) | :white_check_mark: |
+| Multiple Attributes | [ex06_multiple_attributes.cpp](source/examples/ex06_multiple_attributes.cpp) | :white_check_mark: |
 | Interleaved Attributes | [ex07_interleaved_attributes.cpp](source/examples/ex07_interleaved_attributes.cpp) |  |
 | Elements | [ex08_elements.cpp](source/examples/ex08_elements.cpp) |  |
 | Stream | [ex09_stream.cpp](source/examples/ex09_stream.cpp) |  |

source/examples/ex03_uniforms.cpp

@@ -1,59 +1,82 @@
 #include <application.hpp>
 #include <shader.hpp>
 
-
+// The inherited class from "Application" to this example.
 class UniformsApplication : public our::Application {
 
-    our::ShaderProgram program;
-    GLuint vertex_array = 0;
+    our::ShaderProgram program;         // Instance of our shader class.
+    GLuint vertex_array = 0;            // The address of the vertex_array saved on the VRAM.
 
-    glm::vec2 scale = glm::vec2(1,1);
-    glm::vec2 translation = glm::vec2(0,0);
-    glm::vec3 color = glm::vec3(1, 0, 0);
+    glm::vec2 scale = glm::vec2(1,1);           // This vector of size 2 represents scale(size).
+    glm::vec2 translation = glm::vec2(0,0);     // This vector of size 2 represents translation(position).
+    glm::vec3 color = glm::vec3(1, 0, 0);       // This vector of size 3 represents color.
     bool vibrate = false, flicker = false;
 
+    // We need a window with title: "Uniforms", size: {1280, 720}, not full screen.
     our::WindowConfiguration getWindowConfiguration() override {
         return { "Uniforms", {1280, 720}, false };
     }
 
+    // Remember called once before game loop.
     void onInitialize() override {
-        program.create();
-        program.attach("assets/shaders/ex03_uniforms/quad.vert", GL_VERTEX_SHADER);
-        program.attach("assets/shaders/ex03_uniforms/uniform_color.frag", GL_FRAGMENT_SHADER);
-        program.link();
+        program.create();                                                                               // Create a "Program".
+        program.attach("assets/shaders/ex03_uniforms/quad.vert", GL_VERTEX_SHADER);                     // Read vertex shader file, compile it, and check for errors.
+        program.attach("assets/shaders/ex03_uniforms/uniform_color.frag", GL_FRAGMENT_SHADER);          // Read fragment shader file, compile it, and check for errors.
+        program.link();                                                                                 // link to shaders together in the program.
 
-        glGenVertexArrays(1, &vertex_array);
+        glGenVertexArrays(1, &vertex_array);            // Create a vertex array and save address in uint vertex array.
 
-        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);           // Set the screen clear color to black.
     }
 
+    // Remember called in game loop phase every frame.
     void onDraw(double deltaTime) override {
-        glClear(GL_COLOR_BUFFER_BIT);
-        glUseProgram(program);
-
-        GLuint scale_uniform_location = glGetUniformLocation(program, "scale");
-        glUniform2f(scale_uniform_location, scale.x, scale.y);
-        GLuint translation_uniform_location = glGetUniformLocation(program, "translation");
-        glUniform2f(translation_uniform_location, translation.x, translation.y);
-        GLuint color_uniform_location = glGetUniformLocation(program, "color");
-        glUniform3f(color_uniform_location, color.r, color.g, color.b);
+        
+        glClear(GL_COLOR_BUFFER_BIT);               // Clear the frame.
+        glUseProgram(program);                      // Set "program" as the GPU drawing program.
+
+
+        // Set the GPU parameters every frame as the position, scale, color are not permenant values,
+        // they change every frame, unlike the vertex data for example that needs to be set once before
+        // application starts.
+        GLuint scale_uniform_location = glGetUniformLocation(program, "scale");                 // Get the address to the program variable "scale" found
+                                                                                                // in vertex shader "quad.vert file".
+        glUniform2f(scale_uniform_location, scale.x, scale.y);                                  // Set the value of vec2 "scale_uniform_location" with scale data.
+        
+        
+        GLuint translation_uniform_location = glGetUniformLocation(program, "translation");     // Get the address to the program variable "translation" found
+                                                                                                // in vertex shader "quad.vert file".
+        glUniform2f(translation_uniform_location, translation.x, translation.y);                // Set the value of vec2 "translation_uniform_location" with translation data.
+        
+        
+        GLuint color_uniform_location = glGetUniformLocation(program, "color");                 // Get the address to the program variable "color" found
+                                                                                                // in fragment shader "uniform_color.frag file".
+        glUniform3f(color_uniform_location, color.r, color.g, color.b);                         // Set the value of vec3 "color_uniform_location" with color data.
 
         GLuint time_uniform_location = glGetUniformLocation(program, "time");
         glUniform1f(time_uniform_location, glfwGetTime());
+
         GLuint vibrate_uniform_location = glGetUniformLocation(program, "vibrate");
         glUniform1i(vibrate_uniform_location, vibrate);
+
         GLuint flicker_uniform_location = glGetUniformLocation(program, "flicker");
         glUniform1i(flicker_uniform_location, flicker);
 
 
-        glBindVertexArray(vertex_array);
-        glDrawArrays(GL_TRIANGLES, 0, 6);
-        glBindVertexArray(0);
+        glBindVertexArray(vertex_array);        // Bind vertext array (select the buffer to be used by program).
+        
+        glDrawArrays(GL_TRIANGLES, 0, 6);       // Use the buffer and selected program to draw.
+                                                // 1st parameter: Specifies what kind of primitives to render.
+                                                // 2nd parameter: Specifies the starting index in the enabled arrays.
+                                                // 3rd parameter: Specifies the number of indices to be rendered.
+                                                // 3rd parameter is 6 as we draw 2 triangles (each with 3 vertices).
+
+        glBindVertexArray(0);                   // Unbind the array(buffer).
     }
 
     void onDestroy() override {
-        program.destroy();
-        glDeleteVertexArrays(1, &vertex_array);
+        program.destroy();                              // Delete the program.
+        glDeleteVertexArrays(1, &vertex_array);         // Free allocated memory.
     }
 
     void onImmediateGui(ImGuiIO &io) override {

source/examples/ex04_varyings.cpp

@@ -1,38 +1,48 @@
 #include <application.hpp>
 #include <shader.hpp>
 
-
+// The inherited class from "Application" to this example.
 class VaryingsApplication : public our::Application {
 
-    our::ShaderProgram program;
-    GLuint vertex_array = 0;
+    our::ShaderProgram program;         // Instance of our shader class.
+    GLuint vertex_array = 0;            // The address of the vertex_array saved on the VRAM.
 
+    // We need a window with title: "Varyings", size: {1280, 720}, not full screen.
     our::WindowConfiguration getWindowConfiguration() override {
         return { "Varyings", {1280, 720}, false };
     }
 
+    // Remember called once before game loop.
     void onInitialize() override {
-        program.create();
-        program.attach("assets/shaders/ex04_varyings/colored_triangle.vert", GL_VERTEX_SHADER);
-        program.attach("assets/shaders/ex04_varyings/varying_color.frag", GL_FRAGMENT_SHADER);
-        program.link();
+        program.create();                                                                               // Create a "Program".
+        program.attach("assets/shaders/ex04_varyings/colored_triangle.vert", GL_VERTEX_SHADER);         // Read vertex shader file, compile it, and check for errors.
+        program.attach("assets/shaders/ex04_varyings/varying_color.frag", GL_FRAGMENT_SHADER);          // Read fragment shader file, compile it, and check for errors.
+        program.link();                                                                                 // link to shaders together in the program.
 
-        glGenVertexArrays(1, &vertex_array);
+        glGenVertexArrays(1, &vertex_array);            // Create a vertex array and save address in uint vertex array.
 
-        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);           // Set the screen clear color to black.
     }
 
+    // Remember called in game loop phase every frame.
     void onDraw(double deltaTime) override {
-        glClear(GL_COLOR_BUFFER_BIT);
-        glUseProgram(program);
-        glBindVertexArray(vertex_array);
-        glDrawArrays(GL_TRIANGLES, 0, 3);
-        glBindVertexArray(0);
-    }
+
+        glClear(GL_COLOR_BUFFER_BIT);                   // Clear the frame.
+        glUseProgram(program);                          // Set "program" as the GPU drawing program.
+        glBindVertexArray(vertex_array);                // Bind vertext array (select the buffer to be used by program).
+        
+        glDrawArrays(GL_TRIANGLES, 0, 3);               // Use the buffer and selected program to draw.
+                                                        // 1st parameter: Specifies what kind of primitives to render.
+                                                        // 2nd parameter: Specifies the starting index in the enabled arrays.
+                                                        // 3rd parameter: Specifies the number of indices to be rendered.
+                                                        // 3rd parameter is 3 as we draw 1 triangles (each with 3 vertices).
+        
+        glBindVertexArray(0);                           // Unbind the array(buffer).
+    }   
 
     void onDestroy() override {
-        program.destroy();
-        glDeleteVertexArrays(1, &vertex_array);
+        program.destroy();                              // Delete the program.
+        glDeleteVertexArrays(1, &vertex_array);         // Free allocated memory.
     }
 
 };

source/examples/ex05_attributes.cpp

@@ -40,7 +40,11 @@ class AttributesApplication : public our::Application {
         };
 #endif
 
-        glBufferData(GL_ARRAY_BUFFER, 3*3*sizeof(float), positions, GL_STATIC_DRAW);
+        glBufferData(GL_ARRAY_BUFFER, 3*3*sizeof(float), positions, GL_STATIC_DRAW);        // function specifically targeted to copy user-defined data into the currently bound buffer.
+                                                                                            // Its first argument is the type of the buffer we want to copy data into:
+                                                                                            // the vertex buffer object currently bound to the GL_ARRAY_BUFFER target.
+                                                                                            // The second argument specifies the size of the data (in bytes) we want to pass to the buffer;
+                                                                                            // a simple sizeof of the vertex data suffices. The third parameter is the actual data we want to send.
 
         GLuint position_attribute_location = glGetAttribLocation(program, "position");
         std::cout << "Position Attribute Location: " << position_attribute_location << std:: endl;

source/examples/ex06_multiple_attributes.cpp

@@ -32,6 +32,7 @@ class AttributesApplication : public our::Application {
 
         glBufferData(GL_ARRAY_BUFFER, 3*3*sizeof(float), positions, GL_STATIC_DRAW);
 
+        // Setting attribute for (0) the postion.
         glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, (void*)0);
         glEnableVertexAttribArray(0);
 
@@ -46,6 +47,7 @@ class AttributesApplication : public our::Application {
 
         glBufferData(GL_ARRAY_BUFFER, 3*4*sizeof(glm::uint8), colors, GL_STATIC_DRAW);
 
+        // Setting attribute for (1) the color, same as before replicating the process changing the size to 4*sizeof(glm::uint8)
         glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, true, 0, (void*)0);
         glEnableVertexAttribArray(1);