/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */
#if 0
#include <stdlib.h>
#endif

#include "graphics.h"
#include "allfiles.h"

extern int sceneWidth, sceneHeight;
#if 0
extern GLuint backdropTextureName;
#endif

void drawLine(int x1, int y1, int x2, int y2) {
	int x, y;
	bool backwards = false;
#if 0
	if (x1 < 0)  x1 = 0;
	if (y1 < 0)  y1 = 0;
	if (x2 < 0)  x2 = 0;
	if (y2 < 0)  y2 = 0;
	if (x1 > sceneWidth) x1 = sceneWidth - 1;
	if (x2 > sceneWidth) x2 = sceneWidth - 1;
	if (y1 > sceneHeight) y1 = sceneHeight - 1;
	if (y2 > sceneHeight) y2 = sceneHeight - 1;

	if (x1 > x2) {
		x = x2;
		backwards = !backwards;
	} else x = x1;

	if (y1 > y2) {
		y = y2;
		backwards = !backwards;
	} else y = y1;

	int diffX = abs(x2 - x1);
	int diffY = abs(y2 - y1);

	if (! diffX) {
		diffX = 1;
		if (x == sceneWidth - 1) x = sceneWidth - 2;
	}
	if (! diffY) {
		diffY = 1;
		if (y == sceneHeight - 1) y = sceneHeight - 2;
	}
	setPixelCoords(true);


	glLineWidth(2.0);


	int xoffset = 0;
	while (xoffset < diffX) {
		int w = (diffX - xoffset < viewportWidth) ? diffX - xoffset : viewportWidth;

		int yoffset = 0;
		while (yoffset < diffY) {
			int h = (diffY - yoffset < viewportHeight) ? diffY - yoffset : viewportHeight;

			// Render the scene - first the old backdrop
			glBindTexture(GL_TEXTURE_2D, backdropTextureName);
			//glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
			const GLfloat vertices[] = {
				(GLfloat) - x - xoffset, (GLfloat)1 - y - yoffset, 0.,
				(GLfloat)sceneWidth - x - xoffset, (GLfloat)1 - y - yoffset, 0.,
				(GLfloat) - x - xoffset, (GLfloat)sceneHeight - y - yoffset, 0.,
				(GLfloat)sceneWidth - x - xoffset, (GLfloat)sceneHeight - y - yoffset, 0.
			};

			const GLfloat texCoords[] = {
				0.0f, 0.0f,
				backdropTexW, 0.0f,
				0.0f, backdropTexH,
				backdropTexW, backdropTexH
			};


			glUseProgram(shader.texture);

			setPMVMatrix(shader.texture);
			drawQuad(shader.texture, vertices, 1, texCoords);

			// Then the line
			//FIXME:Removing the lines doesn't work, but also didn't work properly before.

			GLint xo1 = -xoffset, xo2 = -xoffset;
			if (! backwards) {
				xo2 += diffX;
			} else {
				xo1 += diffX;
			}
			const GLint lineVertices[] = {
				xo1, -yoffset, 0,
				xo2, -yoffset + diffY, 0,
			};


			glUseProgram(shader.color);

			setPMVMatrix(shader.color);

			glUniform4f(glGetUniformLocation(shader.color, "myColor"), 0.0f, 0.0f, 0.0f, 1.0f);

			int vertexLoc = glGetAttribLocation(shader.color, "myVertex");
			glEnableVertexAttribArray(vertexLoc);
			glVertexAttribPointer(vertexLoc, 3, GL_INT, GL_FALSE, 0, lineVertices);
			glDrawArrays(GL_LINES, 0, 2);
			glDisableVertexAttribArray(vertexLoc);

			glUseProgram(0);

			// Copy Our ViewPort To The Texture
			copyTexSubImage2D(GL_TEXTURE_2D, 0, x + xoffset, y + yoffset, viewportOffsetX, viewportOffsetY, w, h, backdropTextureName);

			yoffset += viewportHeight;
		}
		xoffset += viewportWidth;
	}
	setPixelCoords(false);
#endif
}