add a cube that rotates.

meson.build

@@ -2,5 +2,6 @@ project('opengl-learning', 'cpp', 'c', default_options: ['cpp_std=c++20'])
 
 glfw = dependency('glfw3')
 libepoxy = dependency('epoxy')
+glm = dependency('glm')
 
 subdir('src')

src/main.cc

@@ -1,31 +1,20 @@
 #include <epoxy/gl.h>
 #include <GLFW/glfw3.h>
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
 
 #include <iostream>
 #include <format>
-#include <memory>
 
 #include "shader.hh"
 #include "utilities.hh"
 #include "image.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);
-
-bool wireframe;
-bool rectangleToggled;
-
 struct GlRenderObjects {
 	unsigned int vertexBufferObject;
 	unsigned int vertexArrayObject;
 	unsigned int elementBufferObject;
-	GlRenderObjects(unsigned int vbo, unsigned int vao, unsigned int ebo) {
-		vertexBufferObject = vbo;
-		vertexArrayObject = vao;
-		elementBufferObject = ebo;
-	}
+
 	~GlRenderObjects() {
 		glDeleteBuffers(1, &vertexBufferObject);
 		glDeleteVertexArrays(1, &vertexArrayObject);
@@ -33,7 +22,291 @@ struct GlRenderObjects {
 	}
 };
 
-GlRenderObjects* triangle() {
+enum state {
+	CUBE,
+	RECTANGLE,
+	TRIANGLE
+};
+
+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);
+void createTexture(uint* textureInt, const char* path, GLenum imageType, GLenum minFilter, GLenum magFilter);
+GlRenderObjects cube();
+GlRenderObjects triangle();
+GlRenderObjects rectangle();
+
+bool wireframe;
+bool rectangleToggled;
+state currentState = CUBE;
+
+int main() {
+	glfwInit();
+
+// These brackets are a RAII (Resource Acquisition Is Initialization) pattern,
+// which means these brackets are its own "scope" which means stack allocated memory
+// and heap allocated memory wrapped in a smart pointer like unique_ptr will be cleaned
+// up after you go out of scope.
+{
+	// Set OpenGL version to 3.3.
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
+
+	// Set OpenGL to use the Core profile.
+	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+
+	// Create a OpenGL window with the 800x600 resolution and with the title "OpenGL Sussy Window".
+	GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGL Sussy Window", nullptr, nullptr);
+
+	// Fail if the window is failed to create.
+	if (window == nullptr) {
+		std::cout << "Failed to create GLFW window." << std::endl;
+		glfwTerminate();
+		return -1;
+	}
+
+	glfwMakeContextCurrent(window);
+
+	// Tell OpenGL the size of the rendering window. We're telling it right now that its 800x600.
+	glViewport(0, 0, 800, 600);
+
+	// Register a callback for window size changes.
+	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
+
+	std::string currentPath = utilities::getCurrentPath();
+
+	// Create a shader class.
+	Shader shader(std::format("{}/vertex.glsl", currentPath).c_str(), std::format("{}/fragment.glsl", currentPath).c_str());
+
+	GlRenderObjects cubeRenderObjs = cube();
+	GlRenderObjects triangleRenderObjs = triangle();
+	GlRenderObjects rectangleRenderObjs = rectangle();
+
+	unsigned int texture1, texture2;
+
+	createTexture(&texture1, "container.jpg", GL_RGB, GL_LINEAR_MIPMAP_LINEAR, GL_LINEAR);
+	createTexture(&texture2, "awesomeface.png", GL_RGBA, GL_LINEAR, GL_LINEAR);
+	
+	// activate the shader
+	shader.activate();
+
+	// tell the shader what texture unit the textures are on
+	shader.setInt("texture1", 0);
+	shader.setInt("texture2", 1);
+
+	// glm::mat4 trans = glm::mat4(1.0f);
+	// trans = glm::rotate(trans, glm::radians(90.0f), glm::vec3(0.0, 0.0, 1.0));
+	// trans = glm::scale(trans, glm::vec3(0.5, 0.5, 0.5));
+
+	// Create a render loop, which keeps the program open until glfw tells the loop that the window should close.
+	while (!glfwWindowShouldClose(window)) {
+		// Process input.
+		process_input(window);
+		// Set a callback to trigger whenever a key is pressed.
+		glfwSetKeyCallback(window, key_pressed);
+		
+		// Set the GL state to use this color when clearing the screen.
+		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+		// Clear the screen and use the color from the state.
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+		// assign texture1 to the GL_TEXTURE0 texture unit.
+		glActiveTexture(GL_TEXTURE0);
+		glBindTexture(GL_TEXTURE_2D, texture1);
+
+		// assign texture1 to the GL_TEXTURE1 texture unit.
+		glActiveTexture(GL_TEXTURE1);
+		glBindTexture(GL_TEXTURE_2D, texture2);
+
+		shader.activate();
+
+		// the model matrix. this rotates the plane on the x axis by -55 degrees.
+		glm::mat4 model(1.0f);
+		model = glm::rotate(model, (float)glfwGetTime() * glm::radians(50.0f), glm::vec3(0.5f, 1.0f, 0.0f));
+
+		// the view matrix. this moves the "camera" back by 3 units.
+		glm::mat4 view(1.0f);
+		view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
+
+		// the projection matrix. the fov is 45 degrees. the aspect is 800/600 (4:3). the near plane is 0.1 units. the far plane is 100 units.
+		glm::mat4 projection;
+		projection = glm::perspective(glm::radians(45.0f), 800.0f / 600.0f, 0.1f, 100.0f);
+
+		// create the identity matrix
+		glm::mat4 trans(1);
+		// translate it by this vector3
+		trans = glm::translate(trans, glm::vec3(0.5f, -0.5f, 0.0f));
+		// rotate by the z axis with the angle being controlled by time
+		trans = glm::rotate(trans, (float)glfwGetTime(), glm::vec3(0.0f, 0.0f, 1.0f));
+
+		shader.setMat4("model", model);
+		shader.setMat4("view", view);
+		shader.setMat4("projection", projection);
+
+		switch (currentState) {
+			case CUBE:
+				glEnable(GL_DEPTH_TEST);
+				glBindVertexArray(cubeRenderObjs.vertexArrayObject);
+				glDrawArrays(GL_TRIANGLES, 0, 36);
+				glBindVertexArray(0);
+				glDisable(GL_DEPTH_TEST);
+				break;
+			case RECTANGLE:
+				glBindVertexArray(rectangleRenderObjs.vertexArrayObject);
+				// Draw 6 elements (indices) that are unsigned ints.
+				glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
+				glBindVertexArray(0);
+				break;
+			case TRIANGLE:
+				// Bind the state to use the vertexArrayObject object so OpenGL knows what to do with the verticies.
+				glBindVertexArray(triangleRenderObjs.vertexArrayObject);
+				// Draw the verticies with the first index being 0 and the size of the vertex being 3 floats.
+				glDrawArrays(GL_TRIANGLES, 0, 3);
+				glBindVertexArray(0);
+				break;
+		}
+
+		// This swaps completely drawn frames from the "second buffer" to the front one which is displayed on the screen.
+		glfwSwapBuffers(window);
+		// Check if any events are triggered.
+		glfwPollEvents();
+	}
+}
+
+	glfwTerminate();
+	return 0;
+}
+
+void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
+	// Tell OpenGL the size of the rendering window.
+	glViewport(0, 0, width, height);
+}
+
+void process_input(GLFWwindow* window) {
+	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
+		glfwSetWindowShouldClose(window, true);
+	}
+}
+
+void key_pressed(GLFWwindow *window, int key, int scancode, int action, int mods) {
+	// If the W key is pressed, toggle wireframe mode.
+	if (key == GLFW_KEY_W && action == GLFW_PRESS) {
+		if (!wireframe) {
+			// Render polygons in wireframe mode.
+			glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+			wireframe = true;
+		} else {
+			// Render polygons in fill mode.
+			glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+			wireframe = false;		
+		}
+	}
+
+
+	if (key == GLFW_KEY_R && action == GLFW_PRESS) {
+		currentState = RECTANGLE;
+	} else if (key == GLFW_KEY_T && action == GLFW_PRESS) {
+		currentState = TRIANGLE;
+	} else if (key == GLFW_KEY_C && action == GLFW_PRESS) {
+		currentState = CUBE;
+	}
+}
+
+int check_shader_compilation_status(unsigned int shaderId) {
+	int success;
+	glGetShaderiv(shaderId, GL_COMPILE_STATUS, &success);
+	return success;
+}
+
+void createTexture(uint* textureInt, const char* path, GLenum imageType, GLenum minFilter, GLenum magFilter) {
+	// Create a texture ID and assign it to the textureInt pointer.
+	glGenTextures(1, textureInt);
+	// Bind that texture to the GL_TEXTURE_2D state.
+	glBindTexture(GL_TEXTURE_2D, *textureInt);
+
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minFilter);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magFilter);
+
+	Image texture(utilities::getCurrentPath(path));
+	if (texture.data) {
+		// Read the texture data and assign it to the GL texture.
+		glTexImage2D(GL_TEXTURE_2D, 0, imageType, texture.width, texture.height, 0, imageType, GL_UNSIGNED_BYTE, texture.data);
+		// Generate a mipmap of the texture data.
+		glGenerateMipmap(GL_TEXTURE_2D);
+	} else {
+		std::cout << "Failed to load texture." << std::endl;
+	}
+}
+
+GlRenderObjects cube() {
+	float vertices[] = {
+		-0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
+		0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
+		0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
+		0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
+		-0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
+		-0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
+
+		-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
+		0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
+		0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
+		0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
+		-0.5f,  0.5f,  0.5f,  0.0f, 1.0f,
+		-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
+
+		-0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
+		-0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
+		-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
+		-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
+		-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
+		-0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
+
+		0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
+		0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
+		0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
+		0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
+		0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
+		0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
+
+		-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
+		0.5f, -0.5f, -0.5f,  1.0f, 1.0f,
+		0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
+		0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
+		-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
+		-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
+
+		-0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
+		0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
+		0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
+		0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
+		-0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
+		-0.5f,  0.5f, -0.5f,  0.0f, 1.0f
+	};
+
+	unsigned int vertexArrayObject, vertexBufferObject;
+	glGenVertexArrays(1, &vertexArrayObject);
+	glGenBuffers(1, &vertexBufferObject);
+	glBindVertexArray(vertexArrayObject);
+
+	glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObject);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
+	glEnableVertexAttribArray(0);
+
+	glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
+	glEnableVertexAttribArray(2);
+
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+	glBindVertexArray(0);
+
+	return {vertexBufferObject, vertexArrayObject, 0};
+}
+
+GlRenderObjects triangle() {
 	// An array of verticies containing data for a triangle.
 	float vertices[] = {
 		// positions		// colors		// texture coords
@@ -75,10 +348,10 @@ GlRenderObjects* triangle() {
 	glBindBuffer(GL_ARRAY_BUFFER, 0);
 	glBindVertexArray(0);
 
-	return new GlRenderObjects(vertexBufferObject, vertexArrayObject, 0);
+	return {vertexBufferObject, vertexArrayObject, 0};
 }
 
-GlRenderObjects* rectangle() {
+GlRenderObjects rectangle() {
 	float vertices[] = {
 		// positions		// colors		// texture coords
 		0.5f,  0.5f, 0.0f,	1.0f, 0.0f, 0.0f,	1.0f, 1.0f,
@@ -129,168 +402,5 @@ GlRenderObjects* rectangle() {
 	glBindVertexArray(0);
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 
-	return new GlRenderObjects(vertexBufferObject, vertexArrayObject, elementBufferObject);
-}
-
-int main() {
-	glfwInit();
-
-{
-	// Set OpenGL version to 3.3.
-	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
-	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
-
-	// Set OpenGL to use the Core profile.
-	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-
-	// Create a OpenGL window with the 800x600 resolution and with the title "OpenGL Sussy Window".
-	GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGL Sussy Window", nullptr, nullptr);
-
-	// Fail if the window is failed to create.
-	if (window == nullptr) {
-		std::cout << "Failed to create GLFW window." << std::endl;
-		glfwTerminate();
-		return -1;
-	}
-
-	glfwMakeContextCurrent(window);
-
-	// Tell OpenGL the size of the rendering window. We're telling it right now that its 800x600.
-	glViewport(0, 0, 800, 600);
-
-	// Register a callback for window size changes.
-	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
-
-	std::string currentPath = utilities::getCurrentPath();
-
-	// Create a shader class.
-	Shader shader(std::format("{}/vertex.glsl", currentPath).c_str(), std::format("{}/fragment.glsl", currentPath).c_str());
-
-	std::unique_ptr<GlRenderObjects> triangleRenderObjs(triangle());
-	std::unique_ptr<GlRenderObjects> rectangleRenderObjs(rectangle());
-
-	unsigned int texture1, texture2;
-	
-{
-	glGenTextures(1, &texture1);
-	glBindTexture(GL_TEXTURE_2D, texture1);
-
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-
-	Image texture(utilities::getCurrentPath("container.jpg"));
-	if (texture.data) {
-		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texture.width, texture.height, 0, GL_RGB, GL_UNSIGNED_BYTE, texture.data);
-		glGenerateMipmap(GL_TEXTURE_2D);
-	} else {
-		std::cout << "Failed to load texture." << std::endl;
-	}
-}
-
-{
-	glGenTextures(1, &texture2);
-	glBindTexture(GL_TEXTURE_2D, texture2);
-
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-
-	Image texture(utilities::getCurrentPath("awesomeface.png"));
-
-	if (texture.data) {
-		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture.width, texture.height, 0, GL_RGBA, GL_UNSIGNED_BYTE, texture.data);
-		glGenerateMipmap(GL_TEXTURE_2D);
-	} else {
-		std::cout << "Failed to load texture." << std::endl;
-	}
-}
-
-	// activate the shader
-	shader.activate();
-
-	// tell the shader what texture unit the textures are on
-	shader.setInt("texture1", 0);
-	shader.setInt("texture2", 1);
-
-	// Create a render loop, which keeps the program open until glfw tells the loop that the window should close.
-	while (!glfwWindowShouldClose(window)) {
-		// Process input.
-		process_input(window);
-		// Set a callback to trigger whenever a key is pressed.
-		glfwSetKeyCallback(window, key_pressed);
-		
-		// Set the GL state to use this color when clearing the screen.
-		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
-		// Clear the screen and use the color from the state.
-		glClear(GL_COLOR_BUFFER_BIT);
-
-		glActiveTexture(GL_TEXTURE0);
-		glBindTexture(GL_TEXTURE_2D, texture1);
-		glActiveTexture(GL_TEXTURE1);
-		glBindTexture(GL_TEXTURE_2D, texture2);
-
-		shader.activate();
-
-		if (!rectangleToggled) {
-			// Bind the state to use the vertexArrayObject object so OpenGL knows what to do with the verticies.
-			glBindVertexArray(triangleRenderObjs->vertexArrayObject);
-			// Draw the verticies with the first index being 0 and the size of the vertex being 3 floats.
-			glDrawArrays(GL_TRIANGLES, 0, 3);
-			glBindVertexArray(0);
-		} else {
-			glBindVertexArray(rectangleRenderObjs->vertexArrayObject);
-			// Draw 6 elements (indices) that are unsigned ints.
-			glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
-			glBindVertexArray(0);
-		}
-
-		// This swaps completely drawn frames from the "second buffer" to the front one which is displayed on the screen.
-		glfwSwapBuffers(window);
-		// Check if any events are triggered.
-		glfwPollEvents();
-	}
-}
-
-	glfwTerminate();
-	return 0;
-}
-
-void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
-	// Tell OpenGL the size of the rendering window.
-	glViewport(0, 0, width, height);
-}
-
-void process_input(GLFWwindow* window) {
-	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
-		glfwSetWindowShouldClose(window, true);
-	}
-}
-
-int check_shader_compilation_status(unsigned int shaderId) {
-	int success;
-	glGetShaderiv(shaderId, GL_COMPILE_STATUS, &success);
-	return success;
-}
-
-void key_pressed(GLFWwindow *window, int key, int scancode, int action, int mods) {
-	// If the W key is pressed, toggle wireframe mode.
-	if (key == GLFW_KEY_W && action == GLFW_PRESS) {
-		if (!wireframe) {
-			// Render polygons in wireframe mode.
-			glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
-			wireframe = true;
-		} else {
-			// Render polygons in fill mode.
-			glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
-			wireframe = false;		
-		}
-	}
-
-	// Flip a boolean indicating the rectangle should be rendered.
-	if (key == GLFW_KEY_R && action == GLFW_PRESS) {
-		rectangleToggled = !rectangleToggled;
-	}
+	return {vertexBufferObject, vertexArrayObject, elementBufferObject};
 }

src/meson.build

@@ -12,5 +12,5 @@ vertex = custom_target('vertex', output: 'vertex.glsl', input: 'vertex.glsl', co
 container = custom_target('container', output: 'container.jpg', input: 'container.jpg', command: [copy, '@INPUT@', '@OUTPUT@'])
 awesomeface = custom_target('awesomeface', output: 'awesomeface.png', input: 'awesomeface.png', command: [copy, '@INPUT@', '@OUTPUT@'])
 
-executable('main', [sources, fragment, vertex, container, awesomeface], dependencies: [glfw, libepoxy])
+executable('main', [sources, fragment, vertex, container, awesomeface], dependencies: [glfw, libepoxy, glm])
 executable('fixedfunction', ['fixedfunction.cc'], dependencies: [glfw, libepoxy])

src/shader.cc

@@ -103,3 +103,7 @@ void Shader::setInt(const char* name, int value)  {
 void Shader::setFloat(const char* name, float value) const {
 	glUniform1f(glGetUniformLocation(id, name), value);
 }
+
+void Shader::setMat4(const char* name, glm::mat4 matrix) {
+	glUniformMatrix4fv(glGetUniformLocation(id, name), 1, GL_FALSE, glm::value_ptr(matrix));
+}

src/shader.hh

@@ -2,6 +2,9 @@
 #define SHADER_HH
 #include <string>
 #include <epoxy/gl.h>
+#include <glm/glm.hpp>
+#include <glm/gtc/type_ptr.hpp>
+
 class Shader {
 	public:
 	// The Shader ID.
@@ -17,6 +20,7 @@ class Shader {
 	void setBool(const char* name, bool value) const;  
 	void setInt(const char* name, int value) ;   
 	void setFloat(const char* name, float value) const;
+	void setMat4(const char* name, glm::mat4 matrix);
 	private:
 	uint compileShader(std::string code, GLenum type, std::string shaderTypeName);
 	uint compileVertexShader(std::string code);

src/utilities.cc

@@ -3,7 +3,7 @@
 #include <string>
 #include <sstream>
 #include <unistd.h>
-#include <linux/limits.h>
+#include <limits.h>
 #include <format>
 
 std::string utilities::getCurrentPath() {

src/vertex.glsl

@@ -7,8 +7,13 @@ layout (location = 2) in vec2 aTexCoord;
 out vec3 ourColor;
 out vec2 TexCoord;
 
+uniform mat4 model;
+uniform mat4 view;
+uniform mat4 projection;
+
 void main() {
-	gl_Position = vec4(aPos, 1.0);
+	// matrix multiplication goes from right to left.
+	gl_Position = projection * view * model * vec4(aPos, 1.0);
 	ourColor = aColor;
 	TexCoord = aTexCoord;
 }