Triangle render

CMakeLists.txt

@@ -3,6 +3,13 @@ cmake_minimum_required (VERSION 3.0)
 project (OpenGL_Analog_Clock)
 
 find_package(OpenGL REQUIRED)
+find_package(GLEW REQUIRED)
+find_package(glfw3 REQUIRED)
+
+include_directories(
+    Include/
+    .
+)
 
 set(ALL_LIBS
 	${OPENGL_LIBRARY}
@@ -10,6 +17,8 @@ set(ALL_LIBS
 	GLEW
 )
 
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 -ggdb")
+
 add_definitions(
 	-DTW_STATIC
 	-DTW_NO_LIB_PRAGMA
@@ -20,6 +29,7 @@ add_definitions(
 
 add_executable(clock
     main.c
+    shader.c
 )
 
 target_link_libraries(clock

Include/shader.h

@@ -0,0 +1,6 @@
+#ifndef SHADER_HPP
+#define SHADER_HPP
+
+GLuint LoadShaders(const char *vertex_file_path, const char *fragment_file_path);
+
+#endif

main.c

@@ -7,6 +7,10 @@
 
 // Include GLFW
 #include <GLFW/glfw3.h>
+
+// Include shader
+#include "shader.h"
+
 GLFWwindow* window;
 
 int main(void) {
@@ -49,13 +53,48 @@ int main(void) {
 	// Dark grey background
 	glClearColor(0.15f, 0.15f, 0.15f, 0.0f);
 
+	GLuint VertexArrayID;
+	glGenVertexArrays(1, &VertexArrayID);
+	glBindVertexArray(VertexArrayID);
+
+	// Create and compile our GLSL program from the shaders
+	GLuint programID = LoadShaders("shaders/SimpleVertexShader.vertexshader", "shaders/SimpleFragmentShader.fragmentshader");
+
+	static const GLfloat g_vertex_buffer_data[] = { 
+		-1.0f, -1.0f, 0.0f,
+		 1.0f, -1.0f, 0.0f,
+		 0.0f,  1.0f, 0.0f
+	};
+
+	GLuint vertexbuffer;
+	glGenBuffers(1, &vertexbuffer);
+	glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
+
 	do {
 		// Clear the screen. It's not mentioned before Tutorial 02,
         // but it can cause flickering, so it's there nonetheless.
 		glClear(GL_COLOR_BUFFER_BIT);
 
-		// Draw nothing, see you in tutorial 2 !
+		// Use our shader
+		glUseProgram(programID);
 
+		// 1rst attribute buffer : vertices
+		glEnableVertexAttribArray(0);
+		glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
+		glVertexAttribPointer(
+			0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
+			3,                  // size
+			GL_FLOAT,           // type
+			GL_FALSE,           // normalized?
+			0,                  // stride
+			NULL            // array buffer offset
+		);
+
+		// Draw the triangle !
+		glDrawArrays(GL_TRIANGLES, 0, 3); // 3 indices starting at 0 -> 1 triangle
+
+		glDisableVertexAttribArray(0);
 		
 		// Swap buffers
 		glfwSwapBuffers(window);

shader.c

@@ -0,0 +1,112 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <GL/glew.h>
+
+#include "shader.h"
+
+GLuint LoadShaders(const char *vertex_file_path, const char *fragment_file_path) {
+
+	// Create the shaders
+	GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
+	GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
+
+	// Read the Vertex Shader code from the file
+    FILE *vertex_file;
+    char *vertex_code = malloc(256 * sizeof(char));
+    unsigned int cursor = 0;
+    
+    vertex_file = fopen(vertex_file_path, "r");
+    if (vertex_file == NULL) {
+        fprintf(stderr, "Could not open %s.\n", vertex_file_path);
+        free(vertex_code);
+        return 0;
+    }
+
+    while (!feof(vertex_file)) {
+        vertex_code[cursor] = getc(vertex_file);
+        cursor++;
+    }
+
+	// Read the Fragment Shader code from the file
+    FILE *fragment_file;
+    char *fragment_code = malloc(256 * sizeof(char));
+    cursor = 0;
+    
+    fragment_file = fopen(fragment_file_path, "r");
+    if (fragment_file == NULL) {
+        fprintf(stderr, "Could not open %s.\n", fragment_file_path);
+        free(vertex_code);
+        free(fragment_code);
+        return 0;
+    }
+
+    while (!feof(fragment_file)) {
+        fragment_code[cursor] = getc(fragment_file);
+        cursor++;
+    }
+
+	GLint Result = GL_FALSE;
+	int InfoLogLength;
+
+
+	// Compile Vertex Shader
+	printf("Compiling shader : %s\n", vertex_file_path);
+	glShaderSource(VertexShaderID, 1, (const char **)&vertex_code, NULL);
+	glCompileShader(VertexShaderID);
+
+	// Check Vertex Shader
+	glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
+	glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
+	//if ( InfoLogLength > 0 ){
+	//	std::vector<char> VertexShaderErrorMessage(InfoLogLength+1);
+	//	glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &VertexShaderErrorMessage[0]);
+	//	printf("%s\n", &VertexShaderErrorMessage[0]);
+	//}
+
+
+
+	// Compile Fragment Shader
+	printf("Compiling shader : %s\n", fragment_file_path);
+	glShaderSource(FragmentShaderID, 1, (const char **)&fragment_code, NULL);
+	glCompileShader(FragmentShaderID);
+
+	// Check Fragment Shader
+	glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
+	glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
+	//if ( InfoLogLength > 0 ){
+	//	std::vector<char> FragmentShaderErrorMessage(InfoLogLength+1);
+	//	glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, &FragmentShaderErrorMessage[0]);
+	//	printf("%s\n", &FragmentShaderErrorMessage[0]);
+	//}
+
+
+
+	// Link the program
+	printf("Linking program\n");
+	GLuint ProgramID = glCreateProgram();
+	glAttachShader(ProgramID, VertexShaderID);
+	glAttachShader(ProgramID, FragmentShaderID);
+	glLinkProgram(ProgramID);
+
+	// Check the program
+	glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
+	glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
+	//if ( InfoLogLength > 0 ){
+	//	std::vector<char> ProgramErrorMessage(InfoLogLength+1);
+	//	glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
+	//	printf("%s\n", &ProgramErrorMessage[0]);
+	//}
+
+	
+	glDetachShader(ProgramID, VertexShaderID);
+	glDetachShader(ProgramID, FragmentShaderID);
+	
+	glDeleteShader(VertexShaderID);
+	glDeleteShader(FragmentShaderID);
+
+	return ProgramID;
+}
+
+

shaders/SimpleFragmentShader.fragmentshader

@@ -0,0 +1,12 @@
+#version 330 core
+
+// Ouput data
+out vec3 color;
+
+void main()
+{
+
+	// Output color = red 
+	color = vec3(1,0,0);
+
+}

shaders/SimpleVertexShader.vertexshader

@@ -0,0 +1,12 @@
+#version 330 core
+
+// Input vertex data, different for all executions of this shader.
+layout(location = 0) in vec3 vertexPosition_modelspace;
+
+void main(){
+
+    gl_Position.xyz = vertexPosition_modelspace;
+    gl_Position.w = 1.0;
+
+}
+