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 <mgba-util/math.h>
  9
 10static const GLint _glTexCoords[] = {
 11	0, 0,
 12	1, 0,
 13	1, 1,
 14	0, 1
 15};
 16
 17static void mGLContextInit(struct VideoBackend* v, WHandle handle) {
 18	UNUSED(handle);
 19	struct mGLContext* context = (struct mGLContext*) v;
 20	glGenTextures(2, context->tex);
 21	glBindTexture(GL_TEXTURE_2D, context->tex[0]);
 22	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 23#ifndef _WIN32
 24	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 25	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 26#endif
 27	glBindTexture(GL_TEXTURE_2D, context->tex[1]);
 28	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 29#ifndef _WIN32
 30	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 31	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 32#endif
 33	context->activeTex = 0;
 34}
 35
 36static void mGLContextSetDimensions(struct VideoBackend* v, unsigned width, unsigned height) {
 37	struct mGLContext* context = (struct mGLContext*) v;
 38	v->width = width;
 39	v->height = height;
 40
 41	glBindTexture(GL_TEXTURE_2D, context->tex[0]);
 42#ifdef COLOR_16_BIT
 43#ifdef COLOR_5_6_5
 44	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, 0);
 45#else
 46	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, 0);
 47#endif
 48#elif defined(__BIG_ENDIAN__)
 49	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8_REV, 0);
 50#else
 51	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
 52#endif
 53
 54	glBindTexture(GL_TEXTURE_2D, context->tex[1]);
 55#ifdef COLOR_16_BIT
 56#ifdef COLOR_5_6_5
 57	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, 0);
 58#else
 59	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, 0);
 60#endif
 61#elif defined(__BIG_ENDIAN__)
 62	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8_REV, 0);
 63#else
 64	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, toPow2(width), toPow2(height), 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
 65#endif
 66
 67	context->vertices[0] = 0;
 68	context->vertices[1] = 0;
 69	context->vertices[2] = toPow2(width);
 70	context->vertices[3] = 0;
 71	context->vertices[4] = toPow2(width);
 72	context->vertices[5] = toPow2(height);
 73	context->vertices[6] = 0;
 74	context->vertices[7] = toPow2(height);
 75}
 76
 77static void mGLContextDeinit(struct VideoBackend* v) {
 78	struct mGLContext* context = (struct mGLContext*) v;
 79	glDeleteTextures(2, context->tex);
 80}
 81
 82static void mGLContextResized(struct VideoBackend* v, unsigned w, unsigned h) {
 83	unsigned drawW = w;
 84	unsigned drawH = h;
 85	if (v->lockAspectRatio) {
 86		if (w * v->height > h * v->width) {
 87			drawW = h * v->width / v->height;
 88		} else if (w * v->height < h * v->width) {
 89			drawH = w * v->height / v->width;
 90		}
 91	}
 92	if (v->lockIntegerScaling) {
 93		if (drawW >= v->width) {
 94			drawW -= drawW % v->width;
 95		}
 96		if (drawH >= v->height) {
 97			drawH -= drawH % v->height;
 98		}
 99	}
100	glMatrixMode(GL_MODELVIEW);
101	glLoadIdentity();
102	glClearColor(0, 0, 0, 0);
103	glClear(GL_COLOR_BUFFER_BIT);
104	glViewport((w - drawW) / 2, (h - drawH) / 2, drawW, drawH);
105}
106
107static void mGLContextClear(struct VideoBackend* v) {
108	UNUSED(v);
109	glClearColor(0, 0, 0, 0);
110	glClear(GL_COLOR_BUFFER_BIT);
111}
112
113void mGLContextDrawFrame(struct VideoBackend* v) {
114	struct mGLContext* context = (struct mGLContext*) v;
115	glEnable(GL_TEXTURE_2D);
116	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
117	glEnableClientState(GL_VERTEX_ARRAY);
118	glVertexPointer(2, GL_INT, 0, context->vertices);
119	glTexCoordPointer(2, GL_INT, 0, _glTexCoords);
120	glMatrixMode(GL_PROJECTION);
121	glLoadIdentity();
122	glOrtho(0, v->width, v->height, 0, 0, 1);
123	glMatrixMode(GL_MODELVIEW);
124	glLoadIdentity();
125	if (v->interframeBlending) {
126		glBlendFunc(GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA);
127		glBlendColor(1, 1, 1, 0.5);
128		glBindTexture(GL_TEXTURE_2D, context->tex[context->activeTex ^ 1]);
129		if (v->filter) {
130			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
131			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
132		} else {
133			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
134			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
135		}
136		glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
137		glEnable(GL_BLEND);
138	}
139	glBindTexture(GL_TEXTURE_2D, context->tex[context->activeTex]);
140	if (v->filter) {
141		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
142		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
143	} else {
144		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
145		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
146	}
147	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
148	glDisable(GL_BLEND);
149}
150
151void mGLContextPostFrame(struct VideoBackend* v, const void* frame) {
152	struct mGLContext* context = (struct mGLContext*) v;
153	context->activeTex ^= 1;
154	glBindTexture(GL_TEXTURE_2D, context->tex[context->activeTex]);
155#ifdef COLOR_16_BIT
156#ifdef COLOR_5_6_5
157	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, v->width, v->height, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, frame);
158#else
159	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, v->width, v->height, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, frame);
160#endif
161#elif defined(__BIG_ENDIAN__)
162	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, v->width, v->height, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8_REV, frame);
163#else
164	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, v->width, v->height,  GL_RGBA, GL_UNSIGNED_BYTE, frame);
165#endif
166}
167
168void mGLContextCreate(struct mGLContext* context) {
169	context->d.init = mGLContextInit;
170	context->d.deinit = mGLContextDeinit;
171	context->d.setDimensions = mGLContextSetDimensions;
172	context->d.resized = mGLContextResized;
173	context->d.swap = 0;
174	context->d.clear = mGLContextClear;
175	context->d.postFrame = mGLContextPostFrame;
176	context->d.drawFrame = mGLContextDrawFrame;
177	context->d.setMessage = 0;
178	context->d.clearMessage = 0;
179}