opengl

commit f76ada37bb1470a7c15a1f56f0b83accead0097a
parent d9d61540c09c9eca4f90e4311eda21effff8268a
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Sun, 25 Jun 2023 12:33:38 +0900

shaders

Diffstat:
M
main.c
 | 
104
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--

1 file changed, 102 insertions(+), 2 deletions(-)
diff --git a/main.c b/main.c
@@ -1,9 +1,46 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
 
+float vertices[] = {
+	0.5, 0.5, 0.0,
+	0.5, -0.5, -0.0,
+	-0.5, -0.5, 0.0,
+	-0.5, 0.5, 0.0,
+};
+
+unsigned int indices[] = {
+	0, 1, 3,
+	1, 2, 3,
+};
+
+const char *vertexShaderSource = "
+	#version 330 core
+	layout (location = 0) in vec3 aPos;
+	
+	void
+	main()
+	{
+		gl_Position = vec4(aPos, 1.0);
+	}
+";
+
+const char *fragmentShaderSource = "
+	#version 330 core
+	uniform vec4 ourColor;
+	out vec4 FragColor;
+	
+	void
+	main()
+	{
+		FragColor = ourColor;
+	}
+";
+
+
 void
 framebuffer_size_callback(GLFWwindow *window, int width, int height)
 {
@@ -44,16 +81,79 @@ main(void)
 	// register callback functions
 	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
 	
+	// setup shaders
+	unsigned int vertexShader;
+	int success;
+	char log[512];
+	vertexShader = glCreateShader(GL_VERTEX_SHADER);
+	glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+	glCompileShader(vertexShader);
+	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
+	if (!success) {
+		glGetShaderInfoLog(vertexShader, sizeof(log), NULL, log);
+		fprintf(stderr, "compile vertex shader: %s\n", log);
+		exit(1);
+	}
+	unsigned int fragmentShader;
+	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+	glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
+	glCompileShader(fragmentShader);
+	glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
+	if (!success) {
+		glGetShaderInfoLog(fragmentShader, sizeof(log), NULL, log);
+		fprintf(stderr, "compile fragment shader: %s\n", log);
+		exit(1);
+	}
+	unsigned int shaderProgram;
+	shaderProgram = glCreateProgram();
+	glAttachShader(shaderProgram, vertexShader);
+	glAttachShader(shaderProgram, fragmentShader);
+	glLinkProgram(shaderProgram);
+	glGetShaderiv(shaderProgram, GL_COMPILE_STATUS, &success);
+	if (!success) {
+		glGetShaderInfoLog(shaderProgram, sizeof(log), NULL, log);
+		fprintf(stderr, "link shaders: %s\n", log);
+		exit(1);
+	}
+	glUseProgram(shaderProgram);
+	glDeleteShader(vertexShader);
+	glDeleteShader(fragmentShader);
+	
+	// setup vbo
+	unsigned int VAO, VBO, EBO;
+	glGenVertexArrays(1, &VAO);
+	glGenBuffers(1, &VBO);
+	glGenBuffers(1, &EBO);
+	glBindVertexArray(VAO);
+	glBindBuffer(GL_ARRAY_BUFFER, VBO);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(float),
+		(void *)0);
+	glEnableVertexAttribArray(0);
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,
+		GL_STATIC_DRAW);
+	
 	while (!glfwWindowShouldClose(window)) {
 		processInput(window);
 		
-		glClearColor(0.2, 0.3, 0.3, 1.0);
+		glClearColor(1.0, 1.0, 0.8, 1.0);
 		glClear(GL_COLOR_BUFFER_BIT);
+		
+		float timeValue = glfwGetTime();
+		float greenValue = sinf(timeValue) / 2.0 + 0.5;
+		int vertexColorLocation =
+			glGetUniformLocation(shaderProgram, "ourColor");
+		glUniform4f(vertexColorLocation, 0.0, greenValue, 0.0, 1.0);
+		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
 	
 		glfwPollEvents();
 		glfwSwapBuffers(window);
 	}
-	
+
+	glDeleteVertexArrays(1, &VAO);
+	glDeleteBuffers(1, &VBO);
+	glDeleteProgram(shaderProgram);	
 	glfwTerminate();
 	return 0;
 }