Make a shader class and add colors to the verticies.

.clangd

@@ -0,0 +1,2 @@
+CompileFlags:
+	Add: [-std=c++20]

meson.build

@@ -1,4 +1,4 @@
-project('opengl-learning', 'cpp', 'c')
+project('opengl-learning', 'cpp', 'c', default_options: ['cpp_std=c++20'])
 
 glfw = dependency('glfw3')
 libepoxy = dependency('epoxy')

src/fragment.glsl

@@ -0,0 +1,8 @@
+// Set the GLSL version to 3.3 and use the OpenGL core profile
+#version 330 core
+out vec4 FragColor;
+in vec3 ourColor;
+
+void main() {
+	FragColor = vec4(ourColor, 1.0);
+}

src/main.cc

@@ -1,35 +1,17 @@
-#include <iostream>
 #include <epoxy/gl.h>
 #include <GLFW/glfw3.h>
-#include <cmath>
+
+#include <iostream>
+#include <format>
+
+#include "shader.hh"
+#include "utilities.hh"
 
 void framebuffer_size_callback(GLFWwindow* window, int width, int height);
 void process_input(GLFWwindow* window);
 void key_pressed(GLFWwindow *window, int key, int scancode, int action, int mods);
 int check_shader_compilation_status(unsigned int shaderId);
 
-const char* vertexShaderCode = R"(
-// Set the GLSL version to 3.3 and use the OpenGL core profile
-#version 330 core
-layout (location = 0) in vec3 aPos;
-
-void main() {
-	gl_Position = vec4(aPos, 1.0);
-}
-)";
-
-const char* fragmentShaderCode = R"(
-// Set the GLSL version to 3.3 and use the OpenGL core profile
-#version 330 core
-out vec4 FragColor;
-
-uniform vec4 ourColor;
-
-void main() {
-	FragColor = ourColor;
-}
-)";
-
 bool wireframe;
 bool rectangleToggled;
 
@@ -52,9 +34,10 @@ struct GlRenderObjects {
 GlRenderObjects* triangle() {
 	// An array of verticies containing data for a triangle.
 	float vertices[] = {
-		-0.5f, -0.5f, 0.0f,
-		0.5f, -0.5f, 0.0f,
-		0.0f, 0.5f,  0.0f
+		// positions		// colors
+		-0.5f, -0.5f, 0.0f,	1.0f, 0.0f, 0.0f,
+		0.5f, -0.5f, 0.0f,	0.0f,1.0f, 0.0f,
+		0.0f, 0.5f,  0.0f,	0.0f, 0.0f, 1.0f
 	};
 
 	unsigned int vertexBufferObject, vertexArrayObject;
@@ -71,12 +54,18 @@ GlRenderObjects* triangle() {
 	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
 	// Tell OpenGL how to process the Vertex attributes so it can pass it to the Vertex shader.
-	// This will pass the vertex to the location "0". We tell OpenGL the size of each vertex is 3 floats.
+
+	// This will pass the position attribute to the location "0". We tell OpenGL the size of each position attribute is 3 floats.
 	// We tell OpenGL that we're using floating point types.
 	// We tell OpenGL we don't want our data to be normalized as its already normalized.
-	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
 	glEnableVertexAttribArray(0);
 
+	// Pass the color attribute data to the location 1.
+	// We tell it to offset the data per "vertex" by 3 floats to get the color data instead of the position data.
+	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3*sizeof(float)));
+	glEnableVertexAttribArray(1);
+
 	glBindBuffer(GL_ARRAY_BUFFER, 0);
 	glBindVertexArray(0);
 
@@ -85,10 +74,11 @@ GlRenderObjects* triangle() {
 
 GlRenderObjects* rectangle() {
 	float vertices[] = {
-		0.5f,  0.5f, 0.0f,
-		0.5f, -0.5f, 0.0f,
-		-0.5f, -0.5f, 0.0f,
-		-0.5f,  0.5f, 0.0f
+		// positions		// colors
+		0.5f,  0.5f, 0.0f,	1.0f, 0.0f, 0.0f,
+		0.5f, -0.5f, 0.0f,	0.0f,1.0f, 0.0f,
+		-0.5f, -0.5f, 0.0f,	0.0f, 0.0f, 1.0f,
+		-0.5f,  0.5f, 0.0f,	1.0f, 0.0f, 1.0f
 	};
 
 	unsigned int indices[] = {
@@ -115,10 +105,15 @@ GlRenderObjects* rectangle() {
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementBufferObject);
 	// Copy indicies into the GPU's memory.
 	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
+
 	// Tell OpenGL on how to process the verticies.
-	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)0);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void *)0);
 	glEnableVertexAttribArray(0);
 
+	// Process the color data.
+	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void *)(3*sizeof(float)));
+	glEnableVertexAttribArray(1);
+
 	// Unbind the current buffers and arrays from the state.
 	glBindBuffer(GL_ARRAY_BUFFER, 0);
 	glBindVertexArray(0);
@@ -155,54 +150,10 @@ int main() {
 	// Register a callback for window size changes.
 	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
 
-	unsigned int vertexShader;
-	// Create a OpenGL shader object.
-	vertexShader = glCreateShader(GL_VERTEX_SHADER);
-	// Pass the source code to the state.
-	glShaderSource(vertexShader, 1, &vertexShaderCode, nullptr);
-	// Compile the shader
-	glCompileShader(vertexShader);
+	std::string currentPath = utilities::getCurrentPath();
 
-	int success;
-	char infoLog[512];
-	// Check if the shader successfully compiled.
-	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
-	if (!check_shader_compilation_status(vertexShader)) {
-		glGetShaderInfoLog(vertexShader, 512, nullptr, infoLog);
-		std::cout << "ERROR::SHADER::VERTEX::COMPILIATION_FAILED\n" << infoLog << std::endl;
-	}
-
-	unsigned int fragmentShader;
-	// Create a OpenGL Shader object.
-	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
-	// Give the object the source code of the shader, sent with a single string.
-	glShaderSource(fragmentShader, 1, &fragmentShaderCode, NULL);
-	// Compile the shader.
-	glCompileShader(fragmentShader);
-
-	if (!check_shader_compilation_status(fragmentShader)) {
-		glGetShaderInfoLog(fragmentShader, 512, nullptr, infoLog);
-		std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
-	}
-
-	unsigned int shaderProgram;
-	// Create a OpenGL Shader Program object.
-	shaderProgram = glCreateProgram();
-	// Attach the Vertex Shader to the Shader Program.
-	glAttachShader(shaderProgram, vertexShader);
-	// Attach the Fragment Shader to the Shader Program.
-	glAttachShader(shaderProgram, fragmentShader);
-	// Link the Shader Program.
-	glLinkProgram(shaderProgram);
-
-	glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
-	if (!success) {
-		glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
-		std::cout << "ERROR::SHADER::LINKING::LINKING_FAILED\n" << infoLog << std::endl;
-	}
-
-	glDeleteShader(vertexShader);
-	glDeleteShader(fragmentShader);
+	// Create a shader class.
+	Shader* shader = new Shader(std::format("{}/vertex.glsl", currentPath).c_str(), std::format("{}/fragment.glsl", currentPath).c_str());
 
 	GlRenderObjects* triangleRenderObjs = triangle();
 	GlRenderObjects* rectangleRenderObjs = rectangle();
@@ -219,14 +170,8 @@ int main() {
 		// Clear the screen and use the color from the state.
 		glClear(GL_COLOR_BUFFER_BIT);
 
-		// Use the shaderProgram shader program for drawing verticies.
-		glUseProgram(shaderProgram);
-
-		// Change the uniform color.
-		float timeValue = glfwGetTime();
-		float greenValue = (std::sin(timeValue) / 2.0f) + 0.5f;
-		int vertexColorLocation = glGetUniformLocation(shaderProgram, "ourColor");
-		glUniform4f(vertexColorLocation, 0.0f, greenValue, 0.0f, 1.0f);
+		// activate the shader
+		shader->activate();
 
 		if (!rectangleToggled) {
 			// Bind the state to use the vertexArrayObject object so OpenGL knows what to do with the verticies.
@@ -250,7 +195,7 @@ int main() {
 	// Clean up objects from memory.
 	delete triangleRenderObjs;
 	delete rectangleRenderObjs;
-	glDeleteProgram(shaderProgram);
+	delete shader;
 
 	glfwTerminate();
 	return 0;

src/meson.build

@@ -1,6 +1,14 @@
 sources = [
-	'main.cc'
+	'main.cc',
+	'shader.cc',
+	'utilities.cc'
 ]
 
-executable('main', sources, dependencies: [glfw, libepoxy])
+copy = find_program('cp')
+
+fragment = custom_target('fragment', output: 'fragment.glsl', input: 'fragment.glsl', command: [copy, '@INPUT@', '@OUTPUT@'])
+vertex = custom_target('vertex', output: 'vertex.glsl', input: 'vertex.glsl', command: [copy, '@INPUT@', '@OUTPUT@'])
+
+
+executable('main', [sources] + [fragment, vertex], dependencies: [glfw, libepoxy])
 executable('fixedfunction', ['fixedfunction.cc'], dependencies: [glfw, libepoxy])

src/shader.cc

@@ -0,0 +1,105 @@
+#include "shader.hh"
+#include <fstream>
+#include <sstream>
+#include <iostream>
+#include <epoxy/gl.h>
+#include <format>
+
+Shader::Shader(const char* vertexPath, const char* fragmentPath) {
+	std::string vertexCode, fragmentCode;
+	std::ifstream vShaderFile, fShaderFile;
+
+	vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+	fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+	try {
+		// open shader files.
+		vShaderFile.open(vertexPath);
+		fShaderFile.open(fragmentPath);
+
+		std::stringstream vShaderStream, fShaderStream;
+
+		// read files into stringstreams.
+		vShaderStream << vShaderFile.rdbuf();
+		fShaderStream << fShaderFile.rdbuf();
+
+		// close the file handles.
+		vShaderFile.close();
+		fShaderFile.close();
+
+		// convert the streams into c++ strings.
+		vertexCode = vShaderStream.str();
+		fragmentCode = fShaderStream.str();
+	} catch (std::ifstream::failure e) {
+		std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
+	}
+
+	// compile vertex and fragment shaders.
+	uint vertex, fragment;
+	vertex = compileVertexShader(vertexCode);
+	fragment = compileFragmentShader(fragmentCode);
+
+	// link the shader to a shader program.
+	id = glCreateProgram();
+	glAttachShader(id, vertex);
+	glAttachShader(id, fragment);
+	glLinkProgram(id);
+
+	// check if the shader program successfully linked.
+	int success;
+	char infoLog[512];
+	glGetProgramiv(id, GL_LINK_STATUS, &success);
+	if (!success) {
+		glGetProgramInfoLog(id, 512, nullptr, infoLog);
+		std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED" << std::endl << infoLog << std::endl;
+	}
+
+	// clean up un-needed shader objects.
+	glDeleteShader(vertex);
+	glDeleteShader(fragment);
+}
+
+Shader::~Shader() {
+	glDeleteProgram(id);
+}
+
+uint Shader::compileShader(std::string code, GLenum type, std::string shaderTypeName) {
+	int success;
+	uint shader;
+	char infoLog[512];
+	const char* codeCString = code.c_str();
+
+	shader = glCreateShader(type);
+	glShaderSource(shader, 1, &codeCString, nullptr);
+	glCompileShader(shader);
+	glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
+
+	if (!success) {
+		glGetShaderInfoLog(shader, 512, NULL, infoLog);
+		std::cout << std::format("ERROR::SHADER::{}::COMPILATION_FAILED", shaderTypeName) << std::endl << infoLog << std::endl;
+	}
+
+	return shader;
+}
+
+uint Shader::compileVertexShader(std::string code) {
+	return compileShader(code, GL_VERTEX_SHADER, "VERTEX");
+}
+
+uint Shader::compileFragmentShader(std::string code) {
+	return compileShader(code, GL_FRAGMENT_SHADER, "FRAGMENT");
+}
+
+void Shader::activate() {
+	glUseProgram(id);
+}
+
+void Shader::setBool(const std::string &name, bool value) const {
+	glUniform1f(glGetUniformLocation(id, name.c_str()), (int)value);
+}
+void Shader::setInt(const std::string &name, int value) const {
+	glUniform1f(glGetUniformLocation(id, name.c_str()), value);
+}
+void Shader::setFloat(const std::string &name, float value) const {
+	glUniform1f(glGetUniformLocation(id, name.c_str()), value);
+}

src/shader.hh

@@ -0,0 +1,25 @@
+#ifndef SHADER_HH
+#define SHADER_HH
+#include <string>
+#include <epoxy/gl.h>
+class Shader {
+	public:
+	// The Shader ID.
+	unsigned int id;
+
+	// Constructor that builds the shader from a path of vertex and fragment shaders.
+	Shader(const char* vertexPath, const char* fragmentPath);
+	// Destructor that cleans up memory.
+	~Shader();
+	// activate the shader.
+	void activate();
+    // utility uniform functions
+	void setBool(const std::string &name, bool value) const;  
+	void setInt(const std::string &name, int value) const;   
+	void setFloat(const std::string &name, float value) const;
+	private:
+	uint compileShader(std::string code, GLenum type, std::string shaderTypeName);
+	uint compileVertexShader(std::string code);
+	uint compileFragmentShader(std::string code);
+};
+#endif

src/utilities.cc

@@ -0,0 +1,38 @@
+#include "utilities.hh"
+#include <cstddef>
+#include <string>
+#include <sstream>
+#include <unistd.h>
+#include <linux/limits.h>
+
+std::string utilities::getCurrentPath() {
+	char result[PATH_MAX];
+	ssize_t count = readlink("/proc/self/exe", result, PATH_MAX);
+	std::string executablePath = std::string(result, (count > 0) ? count : 0);
+	std::vector<std::string> stringVector = utilities::splitString(executablePath, '/');
+	stringVector.pop_back();
+	return utilities::combineString(stringVector, '/');
+}
+
+std::vector<std::string> utilities::splitString(std::string string, char delimiter) {
+	size_t last = 0;
+	size_t next = 0;
+	std::vector<std::string> vector;
+	while ((next = string.find(delimiter, last)) != std::string::npos) {
+		vector.push_back(string.substr(last, next-last));
+		last = next + 1;
+	}
+	vector.push_back(string.substr(last));
+	return vector;
+}
+
+std::string utilities::combineString(std::vector<std::string> stringVector, char delimiter) {
+	std::stringstream stringStream;
+	for (auto it = stringVector.begin() ; it != stringVector.end(); it++) {
+		if (it != stringVector.begin()) {
+			stringStream << delimiter;
+		}
+		stringStream << *it;
+	}
+	return stringStream.str();
+}

src/utilities.hh

@@ -0,0 +1,11 @@
+#ifndef UTILITIES_HH
+#define UTILITIES_HH
+#include <string>
+#include <vector>
+
+namespace utilities {
+	std::string getCurrentPath();
+	std::vector<std::string> splitString(std::string string, char delimiter);
+	std::string combineString(std::vector<std::string> stringVector, char delimiter);
+}
+#endif

src/vertex.glsl

@@ -0,0 +1,10 @@
+// Set the GLSL version to 3.3 and use the OpenGL core profile
+#version 330 core
+layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec3 aColor;
+out vec3 ourColor;
+
+void main() {
+	gl_Position = vec4(aPos, 1.0);
+	ourColor = aColor;
+}