initial commit

1 files changed, 203 insertions, 0 deletions

diff --git a/gl.c b/gl.c
new file mode 100644
index 0000000..87c4e65
--- /dev/null
+++ b/gl.c
@@ -0,0 +1,203 @@
+#include "lib/glcorearb.h"
+
+// macro trickery to avoid having to write everything twice
+#define gl_for_each_proc(do)\
+	do(DRAWARRAYS, DrawArrays)\
+	do(DRAWELEMENTS, DrawElements)\
+	do(GENTEXTURES, GenTextures)\
+	do(DELETETEXTURES, DeleteTextures)\
+	do(TEXIMAGE2D, TexImage2D)\
+	do(BINDTEXTURE, BindTexture)\
+	do(TEXPARAMETERI, TexParameteri)\
+	do(GETERROR, GetError)\
+	do(GETINTEGERV, GetIntegerv)\
+	do(ENABLE, Enable)\
+	do(DISABLE, Disable)\
+	do(BLENDFUNC, BlendFunc)\
+	do(DEPTHFUNC, DepthFunc)\
+	do(VIEWPORT, Viewport)\
+	do(CLEARCOLOR, ClearColor)\
+	do(CLEAR, Clear)\
+	do(FINISH, Finish)\
+	do(PIXELSTOREI, PixelStorei)\
+	do(CREATESHADER, CreateShader)\
+	do(DELETESHADER, DeleteShader)\
+	do(CREATEPROGRAM, CreateProgram)\
+	do(SHADERSOURCE, ShaderSource)\
+	do(GETSHADERIV, GetShaderiv)\
+	do(GETSHADERINFOLOG, GetShaderInfoLog)\
+	do(COMPILESHADER, CompileShader)\
+	do(CREATEPROGRAM, CreateProgram)\
+	do(DELETEPROGRAM, DeleteProgram)\
+	do(ATTACHSHADER, AttachShader)\
+	do(LINKPROGRAM, LinkProgram)\
+	do(GETPROGRAMIV, GetProgramiv)\
+	do(GETPROGRAMINFOLOG, GetProgramInfoLog)\
+	do(USEPROGRAM, UseProgram)\
+	do(GETATTRIBLOCATION, GetAttribLocation)\
+	do(GETUNIFORMLOCATION, GetUniformLocation)\
+	do(GENBUFFERS, GenBuffers)\
+	do(DELETEBUFFERS, DeleteBuffers)\
+	do(BINDBUFFER, BindBuffer)\
+	do(BUFFERDATA, BufferData)\
+	do(VERTEXATTRIBPOINTER, VertexAttribPointer)\
+	do(VERTEXATTRIBIPOINTER, VertexAttribIPointer)\
+	do(ENABLEVERTEXATTRIBARRAY, EnableVertexAttribArray)\
+	do(DISABLEVERTEXATTRIBARRAY, DisableVertexAttribArray)\
+	do(GENVERTEXARRAYS, GenVertexArrays)\
+	do(DELETEVERTEXARRAYS, DeleteVertexArrays)\
+	do(BINDVERTEXARRAY, BindVertexArray)\
+	do(ACTIVETEXTURE, ActiveTexture)\
+	do(UNIFORM1F, Uniform1f)\
+	do(UNIFORM2F, Uniform2f)\
+	do(UNIFORM3F, Uniform3f)\
+	do(UNIFORM4F, Uniform4f)\
+	do(UNIFORM1I, Uniform1i)\
+	do(UNIFORM2I, Uniform2i)\
+	do(UNIFORM3I, Uniform3i)\
+	do(UNIFORM4I, Uniform4i)\
+	do(UNIFORMMATRIX4FV, UniformMatrix2fv)\
+	do(UNIFORMMATRIX4FV, UniformMatrix3fv)\
+	do(UNIFORMMATRIX4FV, UniformMatrix4fv)\
+	do(DEBUGMESSAGECALLBACK, DebugMessageCallback)\
+	do(DEBUGMESSAGECONTROL, DebugMessageControl)\
+	do(POLYGONMODE, PolygonMode)\
+	do(GENFRAMEBUFFERS, GenFramebuffers)\
+	do(BINDFRAMEBUFFER, BindFramebuffer)\
+	do(FRAMEBUFFERTEXTURE2D, FramebufferTexture2D)\
+	do(DELETEFRAMEBUFFERS, DeleteFramebuffers)\
+	do(BLITFRAMEBUFFER, BlitFramebuffer)\
+	do(DRAWBUFFER, DrawBuffer)\
+	do(TEXIMAGE2DMULTISAMPLE, TexImage2DMultisample)\
+	do(GENRENDERBUFFERS, GenRenderbuffers)\
+	do(DELETERENDERBUFFERS, DeleteRenderbuffers)\
+	do(BINDRENDERBUFFER, BindRenderbuffer)\
+	do(RENDERBUFFERSTORAGE, RenderbufferStorage)\
+	do(RENDERBUFFERSTORAGEMULTISAMPLE, RenderbufferStorageMultisample)\
+	do(FRAMEBUFFERRENDERBUFFER, FramebufferRenderbuffer)\
+	do(CHECKFRAMEBUFFERSTATUS, CheckFramebufferStatus)
+
+#define gl_declare_proc(upper, lower) static PFNGL##upper##PROC gl##lower;
+gl_for_each_proc(gl_declare_proc)
+#undef gl_declare_proc
+
+static void gl_get_procs(void) {
+#if __GNUC__ && !__clang__
+	#pragma GCC diagnostic push
+	#pragma GCC diagnostic ignored "-Wpedantic"
+#endif
+	#define gl_get_proc(upper, lower) gl##lower = (PFNGL##upper##PROC)SDL_GL_GetProcAddress("gl" #lower);
+	gl_for_each_proc(gl_get_proc)
+	#undef gl_get_proc
+#if __GNUC__ && !__clang__
+	#pragma GCC diagnostic pop
+#endif
+}
+
+#define BUFFER_BATCH_SIZE 8
+#define VARRAY_BATCH_SIZE 8
+static GLuint gl_buffers[BUFFER_BATCH_SIZE], gl_buffers_used = BUFFER_BATCH_SIZE;
+static GLuint gl_varrays[VARRAY_BATCH_SIZE], gl_varrays_used = VARRAY_BATCH_SIZE;
+
+
+static GLuint gl_gen_buffer(void) {
+	if (gl_buffers_used >= BUFFER_BATCH_SIZE) {
+		gl_buffers_used = 0;
+		glGenBuffers(BUFFER_BATCH_SIZE, gl_buffers);
+	}
+	return gl_buffers[gl_buffers_used++];
+}
+
+static GLuint gl_gen_vertex_array(void) {
+	if (gl_varrays_used >= VARRAY_BATCH_SIZE) {
+		gl_varrays_used = 0;
+		glGenVertexArrays(VARRAY_BATCH_SIZE, gl_varrays);
+	}
+	return gl_varrays[gl_varrays_used++];
+}
+
+
+// compile a GLSL shader
+static GLuint gl_compile_shader(char const *code, GLenum shader_type) {
+	GLuint shader = glCreateShader(shader_type);
+	glShaderSource(shader, 1, &code, NULL);
+	glCompileShader(shader);
+	GLint status = 0;
+	glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
+	if (status == GL_FALSE) {
+		char log[1024] = {0};
+		glGetShaderInfoLog(shader, sizeof log - 1, NULL, log);
+		debug_println("Error compiling shader: %s", log);
+		return 0;
+	}
+	return shader;
+}
+
+// link together GL shaders
+static GLuint gl_link_program(GLuint *shaders, size_t count) {
+	GLuint program = glCreateProgram();
+	if (program) {
+		for (size_t i = 0; i < count; ++i) {
+			if (!shaders[i]) {
+				glDeleteProgram(program);
+				return 0;
+			}
+			glAttachShader(program, shaders[i]);
+		}
+		glLinkProgram(program);
+		GLint status = 0;
+		glGetProgramiv(program, GL_LINK_STATUS, &status);
+		if (status == GL_FALSE) {
+			char log[1024] = {0};
+			glGetProgramInfoLog(program, sizeof log - 1, NULL, log);
+			debug_println("Error linking shaders: %s", log);
+			glDeleteProgram(program);
+			return 0;
+		}
+	}
+	return program;
+}
+
+static GLuint gl_compile_and_link_shaders(char const *vshader_code, char const *fshader_code) {
+	GLuint shaders[2];
+	shaders[0] = gl_compile_shader(vshader_code, GL_VERTEX_SHADER);
+	shaders[1] = gl_compile_shader(fshader_code, GL_FRAGMENT_SHADER);
+	GLuint program = gl_link_program(shaders, 2);
+	if (shaders[0]) glDeleteShader(shaders[0]);
+	if (shaders[1]) glDeleteShader(shaders[1]);
+	if (program) {
+		debug_print("Successfully linked program %u.\n", program);
+	}
+	return program;
+}
+
+static GLuint gl_create_program_from_files(char const *vshader_file, char const *fshader_file) {
+	char *vcode = read_file_contents(vshader_file);
+	char *fcode = read_file_contents(fshader_file);
+	GLuint program = 0;
+	if (vcode && fcode) {
+		program = gl_compile_and_link_shaders(vcode, fcode);
+	} else {
+		debug_print("WARNING: Couldn't read file: %s.\n", vcode ? fshader_file : vshader_file);
+	}
+	free(vcode); free(fcode);
+	return program;
+}
+
+static GLuint gl_attrib_loc(GLuint program, char const *attrib) {
+	GLint loc = glGetAttribLocation(program, attrib);
+	if (loc == -1) {
+		debug_print("Couldn't find vertex attribute %s.\n", attrib);
+		return 0;
+	}
+	return (GLuint)loc;
+}
+
+static GLint gl_uniform_loc(GLuint program, char const *uniform) {
+	GLint loc = glGetUniformLocation(program, uniform);
+	if (loc == -1) {
+		debug_print("Couldn't find uniform: %s.\n", uniform);
+		return -1;
+	}
+	return loc;
+}