1/* Copyright (c) 2013-2015 Jeffrey Pfau
  2 *
  3 * This Source Code Form is subject to the terms of the Mozilla Public
  4 * License, v. 2.0. If a copy of the MPL was not distributed with this
  5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  6#include "gl.h"
  7
  8#include "util/math.h"
  9
 10static const GLint _glVertices[] = {
 11	0, 0,
 12	256, 0,
 13	256, 256,
 14	0, 256
 15};
 16
 17static const GLint _glTexCoords[] = {
 18	0, 0,
 19	1, 0,
 20	1, 1,
 21	0, 1
 22};
 23
 24static void GBAGLContextInit(struct VideoBackend* v, unsigned width, unsigned height, WHandle handle) {
 25	UNUSED(handle);
 26	struct GBAGLContext* context = (struct GBAGLContext*) v;
 27	glGenTextures(1, &context->tex);
 28	glBindTexture(GL_TEXTURE_2D, context->tex);
 29	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 30#ifndef _WIN32
 31	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 32	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 33#endif
 34	v->width = width;
 35	v->height = height;
 36
 37#ifdef COLOR_16_BIT
 38#ifdef COLOR_5_6_5
 39	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, 0);
 40#else
 41	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, 0);
 42#endif
 43#else
 44	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
 45#endif
 46}
 47
 48static void GBAGLContextDeinit(struct VideoBackend* v) {
 49	struct GBAGLContext* context = (struct GBAGLContext*) v;
 50	glDeleteTextures(1, &context->tex);
 51}
 52
 53static void GBAGLContextResized(struct VideoBackend* v, unsigned w, unsigned h) {
 54	unsigned drawW = w;
 55	unsigned drawH = h;
 56	if (v->lockAspectRatio) {
 57		if (w * v->height > h * v->width) {
 58			drawW = h * v->width / v->height;
 59		} else if (w * v->height < h * v->width) {
 60			drawH = w * v->height / v->width;
 61		}
 62	}
 63	glMatrixMode(GL_MODELVIEW);
 64	glLoadIdentity();
 65	glClearColor(0, 0, 0, 0);
 66	glClear(GL_COLOR_BUFFER_BIT);
 67	glViewport((w - drawW) / 2, (h - drawH) / 2, drawW, drawH);
 68}
 69
 70static void GBAGLContextClear(struct VideoBackend* v) {
 71	UNUSED(v);
 72	glClearColor(0, 0, 0, 0);
 73	glClear(GL_COLOR_BUFFER_BIT);
 74}
 75
 76void GBAGLContextDrawFrame(struct VideoBackend* v) {
 77	struct GBAGLContext* context = (struct GBAGLContext*) v;
 78	glEnable(GL_TEXTURE_2D);
 79	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
 80	glEnableClientState(GL_VERTEX_ARRAY);
 81	glVertexPointer(2, GL_INT, 0, _glVertices);
 82	glTexCoordPointer(2, GL_INT, 0, _glTexCoords);
 83	glMatrixMode(GL_PROJECTION);
 84	glLoadIdentity();
 85	glOrtho(0, v->width, v->height, 0, 0, 1);
 86	glMatrixMode(GL_MODELVIEW);
 87	glLoadIdentity();
 88	glBindTexture(GL_TEXTURE_2D, context->tex);
 89	if (v->filter) {
 90		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 91		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 92	} else {
 93		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 94		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 95	}
 96	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 97}
 98
 99void GBAGLContextPostFrame(struct VideoBackend* v, const void* frame) {
100	struct GBAGLContext* context = (struct GBAGLContext*) v;
101	glBindTexture(GL_TEXTURE_2D, context->tex);
102#ifdef COLOR_16_BIT
103#ifdef COLOR_5_6_5
104	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, v->width, v->height, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, frame);
105#else
106	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, v->width, v->height, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, frame);
107#endif
108#else
109	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, v->width, v->height,  GL_RGBA, GL_UNSIGNED_BYTE, frame);
110#endif
111}
112
113void GBAGLContextCreate(struct GBAGLContext* context) {
114	context->d.init = GBAGLContextInit;
115	context->d.deinit = GBAGLContextDeinit;
116	context->d.resized = GBAGLContextResized;
117	context->d.swap = 0;
118	context->d.clear = GBAGLContextClear;
119	context->d.postFrame = GBAGLContextPostFrame;
120	context->d.drawFrame = GBAGLContextDrawFrame;
121	context->d.setMessage = 0;
122	context->d.clearMessage = 0;
123}