Shaders

6 files changed, 162 insertions, 62 deletions

diff --git a/Tupfile b/Tupfile
index 3ade1a2..d3f0469 100644
--- a/Tupfile
+++ b/Tupfile
@@ -1,6 +1,6 @@
 CC      = gcc
 LD      = $(CC) -fuse-ld=mold
-CFLAGS  = -std=c99 -Wall -Wextra -Iglad
+CFLAGS  = -std=c99 -Wall -Wextra -Iglad -Isrc
 LDFLAGS = -lGL -lglfw
 
 .gitignore
diff --git a/src/fragment.glsl b/src/fragment.glsl
index ca4fb1f..d2dad75 100644
--- a/src/fragment.glsl
+++ b/src/fragment.glsl
@@ -1,8 +1,11 @@
 #version 330 core
 out vec4 FragColor;
 
+uniform vec4 ourColor;
+in vec4 vertexColor;
+
 void
 main()
 {
-	FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);
+	FragColor = vertexColor * ourColor;
 }
diff --git a/src/main.c b/src/main.c
index 4add491..4dfe6b6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,3 +1,4 @@
+#include "shader.h"
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
 #include <stdio.h>
@@ -40,10 +41,10 @@ main([[maybe_unused]] int argc, [[maybe_unused]] char **argv)
 	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
 
 	static const float verts[] = {
-		 0.5f,  0.5f, 0.0f, // top right
-		 0.5f, -0.5f, 0.0f, // bottom right
-		-0.5f, -0.5f, 0.0f, // bottom left
-		-0.5f,  0.5f, 0.0f  // top left
+		 0.5f,  0.5f, 0.0f,  1.0f, 0.0f, 1.0f, // top right
+		 0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f, // bottom right
+		-0.5f, -0.5f, 0.0f,  0.0f, 0.0f, 1.0f, // bottom left
+		-0.5f,  0.5f, 0.0f,  0.0f, 1.0f, 0.0f  // top left
 	};
 	static const GLuint indices[] = {
 		0, 1, 3, // first triangle
@@ -52,57 +53,6 @@ main([[maybe_unused]] int argc, [[maybe_unused]] char **argv)
 	GLuint VBO;
 	glGenBuffers(1, &VBO);
 
-	const GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
-	if (vertex_shader == 0) {
-		fprintf(stderr, "glCreateShader failed\n");
-		return 1;
-	}
-	const char *const vertex_source = (const char*)src_vertex_glsl;
-	glShaderSource(vertex_shader, 1, &vertex_source, NULL);
-	glCompileShader(vertex_shader);
-	int success;
-	glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
-	if (!success) {
-		char info_log[512];
-		glGetShaderInfoLog(vertex_shader, 512, NULL, info_log);
-		fprintf(stderr, "glCompileShader failed:\n%s\n", info_log);
-		return 1;
-	}
-
-	const GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
-	if (fragment_shader == 0) {
-		fprintf(stderr, "glCreateShader failed\n");
-		return 1;
-	}
-	const char *const fragment_source = (const char*)src_fragment_glsl;
-	glShaderSource(fragment_shader, 1, &fragment_source, NULL);
-	glCompileShader(fragment_shader);
-	glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
-	if (!success) {
-		char info_log[512];
-		glGetShaderInfoLog(fragment_shader, 512, NULL, info_log);
-		fprintf(stderr, "glCompileShader failed:\n%s\n", info_log);
-		return 1;
-	}
-
-	const GLuint shader_program = glCreateProgram();
-	if (shader_program == 0) {
-		fprintf(stderr, "glCreateProgram failed\n");
-		return 1;
-	}
-	glAttachShader(shader_program, vertex_shader);
-	glAttachShader(shader_program, fragment_shader);
-	glLinkProgram(shader_program);
-	glDeleteShader(vertex_shader);
-	glDeleteShader(fragment_shader);
-	glGetProgramiv(shader_program, GL_LINK_STATUS, &success);
-	if (!success) {
-		char info_log[512];
-		glGetProgramInfoLog(shader_program, 512, NULL, info_log);
-		fprintf(stderr, "glLinkProgram failed:\n%s\n", info_log);
-		return 1;
-	}
-
 	GLuint EBO;
 	glGenBuffers(1, &EBO);
 
@@ -112,13 +62,30 @@ main([[maybe_unused]] int argc, [[maybe_unused]] char **argv)
 	glBindBuffer(GL_ARRAY_BUFFER, VBO);
 	glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW);
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
-	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
-	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), NULL);
+	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices) / 2, indices, GL_STATIC_DRAW);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
 	glEnableVertexAttribArray(0);
+	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
+	glEnableVertexAttribArray(1);
+
+	Shader shader;
+	if (shader_init(&shader,
+	                (const char *)src_vertex_glsl,
+	                (const char *)src_fragment_glsl))
+	{
+		fprintf(stderr, "shader_init failed\n");
+		return 1;
+	}
+
+	const GLint vertex_color_location =
+	    shader_uniform_location(&shader, "ourColor");
 
-	glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+	//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 	while (!glfwWindowShouldClose(window)) {
-		glUseProgram(shader_program);
+		shader_use(&shader);
+		const int r = 0;//rand();
+		glUniform4f(vertex_color_location,
+		            !(r&1), !(r&2), !(r&4), !(r&8));
 		glBindVertexArray(VAO);
 		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
 
diff --git a/src/shader.c b/src/shader.c
new file mode 100644
index 0000000..d6f1e37
--- /dev/null
+++ b/src/shader.c
@@ -0,0 +1,109 @@
+#include "shader.h"
+#include <stdio.h>
+
+static GLuint create_shader(GLenum shader_type, const char *src);
+static GLuint create_program(GLuint vertex_shader, GLuint fragment_shader);
+
+int
+shader_init(Shader *s, const char *vertex_src, const char *fragment_src)
+{
+	const GLuint vertex_shader = create_shader(GL_VERTEX_SHADER, vertex_src);
+	if (vertex_shader == 0) {
+		fprintf(stderr, "create_shader vertex failed\n");
+		return -1;
+	}
+
+	const GLuint fragment_shader = create_shader(GL_FRAGMENT_SHADER, fragment_src);
+	if (fragment_shader == 0) {
+		fprintf(stderr, "create_shader fragment failed\n");
+		glDeleteShader(vertex_shader);
+		return -1;
+	}
+
+	const GLuint program = create_program(vertex_shader, fragment_shader);
+	glDeleteShader(vertex_shader);
+	glDeleteShader(fragment_shader);
+	if (program == 0) {
+		fprintf(stderr, "create_program failed\n");
+		return -1;
+	}
+
+	s->id = program;
+	return 0;
+}
+
+void
+shader_deinit(Shader *s)
+{
+	if (s->id) {
+		glDeleteProgram(s->id);
+		s->id = 0;
+	}
+}
+
+void
+shader_use(const Shader *s)
+{
+	glUseProgram(s->id);
+}
+
+int
+shader_uniform_location(const Shader *s, const char *name)
+{
+	const GLint location = glGetUniformLocation(s->id, name);
+	if (location < -1) {
+		fprintf(stderr, "glGetUniformLocation failed with '%s'\n", name);
+		return -1;
+	}
+	return location;
+}
+
+static GLuint
+create_shader(GLenum shader_type, const char *src)
+{
+	const GLuint shader = glCreateShader(shader_type);
+	if (shader == 0) {
+		fprintf(stderr, "glCreateShader failed\n");
+		return 0;
+	}
+	glShaderSource(shader, 1, &src, NULL);
+	glCompileShader(shader);
+
+	int success;
+	glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
+	if (!success) {
+		char info_log[512];
+		glGetShaderInfoLog(shader, 512, NULL, info_log);
+		fprintf(stderr, "glCompileShader failed:\n%s\n", info_log);
+		glDeleteShader(shader_type);
+		return 0;
+	}
+
+	return shader;
+}
+
+static GLuint
+create_program(GLuint vertex_shader, GLuint fragment_shader)
+{
+	const GLuint program = glCreateProgram();
+	if (program == 0) {
+		fprintf(stderr, "glCreateProgram failed\n");
+		return 0;
+	}
+
+	glAttachShader(program, vertex_shader);
+	glAttachShader(program, fragment_shader);
+	glLinkProgram(program);
+
+	int success;
+	glGetProgramiv(program, GL_LINK_STATUS, &success);
+	if (!success) {
+		char info_log[512];
+		glGetProgramInfoLog(program, 512, NULL, info_log);
+		fprintf(stderr, "glLinkProgram failed:\n%s\n", info_log);
+		glDeleteProgram(program);
+		return 0;
+	}
+
+	return program;
+}
diff --git a/src/shader.h b/src/shader.h
new file mode 100644
index 0000000..cd44e80
--- /dev/null
+++ b/src/shader.h
@@ -0,0 +1,17 @@
+#pragma once
+#include <glad/glad.h>
+
+typedef struct {
+	GLuint id;
+} Shader;
+
+[[nodiscard]]
+/* Return -1 on error. */
+int shader_init(Shader *s, const char *vertex_src, const char *fragment_src);
+
+void shader_deinit(Shader *s);
+
+void shader_use(const Shader *s);
+
+/* Return -1 on error. */
+GLint shader_uniform_location(const Shader *s, const char *name);
diff --git a/src/vertex.glsl b/src/vertex.glsl
index 2ad10d2..bce2ec6 100644
--- a/src/vertex.glsl
+++ b/src/vertex.glsl
@@ -1,8 +1,12 @@
 #version 330 core
 layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec3 aColor;
+
+out vec4 vertexColor;
 
 void
 main()
 {
-	gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
+	gl_Position = vec4(aPos, 1.0);
+	vertexColor = vec4(aColor, 1.0);
 }