1 files changed, 186 insertions, 0 deletions
diff --git a/src/shader.c b/src/shader.c
new file mode 100644
index 0000000..eefcfc2
--- /dev/null
+++ b/src/shader.c
@@ -0,0 +1,186 @@
+#include <GL/glew.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "voxel.h"
+#include "shader.h"
+
+static char *read_file(const char *filename)
+{
+	FILE *file;
+	long length, read;
+	char *buffer;
+
+	file = fopen(filename, "r");
+	if (file == NULL) {
+		ERROR("could not read file: %s", filename);
+		return NULL;
+	}
+
+	fseek(file, 0, SEEK_END);
+	length = ftell(file);
+	fseek(file, 0, SEEK_SET);
+
+	buffer = malloc(length + 1);
+	read = fread(buffer, 1, length, file);
+	buffer[length] = 0;
+
+	if (read < length) {
+		ERROR("could not read file: %s", filename);
+		free(buffer);
+		return NULL;
+	}
+
+	fclose(file);
+	return buffer;
+}
+
+static void print_shader_log(const char *filename, GLuint id)
+{
+	GLint log_len;
+	char *log;
+	glGetShaderiv(id, GL_INFO_LOG_LENGTH, &log_len);
+	log = malloc(log_len + 1);
+	glGetShaderInfoLog(id, log_len, &log_len, log);
+	log[log_len] = 0;
+	ERROR("failed to compile shader: '%s'\n%s", filename, log);
+	free(log);
+}
+
+static int compile_shader(GLuint *out, const char *filename, const char *code, GLenum type)
+{
+	GLuint id;
+	GLint status;
+	int code_len;
+
+	id = glCreateShader(type);
+	code_len = strlen(code);
+	glShaderSource(id, 1, &code, &code_len);
+	glCompileShader(id);
+	glGetShaderiv(id, GL_COMPILE_STATUS, &status);
+	if (status == GL_FALSE) {
+		print_shader_log(filename, id);
+		glDeleteShader(id);
+		return 1;
+	}
+
+	*out = id;
+	return 0;
+}
+
+static void parse_bind_attributes(Shader *shader, char *code)
+{
+	char *line, *last_line;
+	char *token, *last_token;
+	int attribute = 0;
+
+	line = strtok_r(code, "\n", &last_line);
+	for (; line != NULL; line = strtok_r(NULL, "\n", &last_line)) {
+		token = strtok_r(line, " \t", &last_token);
+		if (strcmp(token, "in") != 0)
+			continue;
+
+		token = strtok_r(NULL, " \t", &last_token);
+		token = strtok_r(NULL, " \t", &last_token);
+		*strchr(token, ';') = 0;
+
+		glBindAttribLocation(shader->program_id, attribute, token);
+		attribute++;
+	}
+}
+
+Shader *shader_init(const char *vertex_file, const char *fragment_file)
+{
+	Shader *shader;
+	char *vertex, *fragment;
+
+	shader = malloc(sizeof(Shader));
+	memset(shader, 0, sizeof(Shader));
+
+	// read shader code from file
+	vertex = read_file(vertex_file);
+	fragment = read_file(fragment_file);
+	if (!vertex || !fragment)
+		goto failure;
+
+	// compile shaders
+	if (compile_shader(&shader->vertex_id, vertex_file, vertex, GL_VERTEX_SHADER))
+		goto failure;
+	if (compile_shader(&shader->fragment_id, fragment_file, fragment,
+			   GL_FRAGMENT_SHADER))
+		goto failure;
+
+	shader->program_id = glCreateProgram();
+	glAttachShader(shader->program_id, shader->vertex_id);
+	glAttachShader(shader->program_id, shader->fragment_id);
+	parse_bind_attributes(shader, vertex);
+	glLinkProgram(shader->program_id);
+	glValidateProgram(shader->program_id);
+
+	if (vertex)
+		free(vertex);
+	if (fragment)
+		free(fragment);
+
+	return shader;
+
+failure:
+	if (vertex)
+		free(vertex);
+	if (fragment)
+		free(fragment);
+	free(shader);
+	return NULL;
+}
+
+void shader_bind(Shader *shader)
+{
+	glEnable(GL_DEPTH_TEST);
+	glEnable(GL_CULL_FACE);
+	glCullFace(GL_BACK);
+	glFrontFace(GL_CW);
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	glUseProgram(shader->program_id);
+}
+
+void shader_unbind(void)
+{
+	glDisable(GL_CULL_FACE);
+	glUseProgram(0);
+}
+
+void shader_free(Shader *shader)
+{
+	glDetachShader(shader->program_id, shader->vertex_id);
+	glDetachShader(shader->program_id, shader->fragment_id);
+	glDeleteShader(shader->vertex_id);
+	glDeleteShader(shader->fragment_id);
+	glDeleteProgram(shader->program_id);
+	free(shader);
+}
+
+GLint shader_uniform_location(Shader *shader, const char *name)
+{
+	return glGetUniformLocation(shader->program_id, name);
+}
+
+void shader_loadf(GLint location, float value)
+{
+	glUniform1f(location, value);
+}
+
+void shader_loadi(GLint location, int value)
+{
+	glUniform1i(location, value);
+}
+
+void shader_loadv3f(GLint location, vec3 value)
+{
+	glUniform3f(location, value[0], value[1], value[2]);
+}
+
+void shader_loadm4f(GLint location, mat4 value)
+{
+	glUniformMatrix4fv(location, 1, GL_FALSE, (float *)value);
+}