text: /*
  * Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
  *
  * This software is provided 'as-is', without any express or implied
  * warranty.  In no event will the authors be held liable for any damages
  * arising from the use of this software.
  * Permission is granted to anyone to use this software for any purpose,
  * including commercial applications, and to alter it and redistribute it
  * freely, subject to the following restrictions:
  * 1. The origin of this software must not be misrepresented; you must not
  * claim that you wrote the original software. If you use this software
  * in a product, an acknowledgment in the product documentation would be
  * appreciated but is not required.
  * 2. Altered source versions must be plainly marked as such, and must not be
  * misrepresented as being the original software.
  * 3. This notice may not be removed or altered from any source distribution.
  */
  
  #include "Render.h"
  
  #ifdef __APPLE__
  #include <GLUT/glut.h>
  #else
  #include "freeglut/GL/glut.h"
  #endif
  
  #include <cstdio>
  #include <cstdarg>
  
  void DebugDraw::DrawPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color)
  {
  	glColor3f(color.r, color.g, color.b);
  	glBegin(GL_LINE_LOOP);
  	for (int32 i = 0; i < vertexCount; ++i)
  	{
  		glVertex2f(vertices[i].x, vertices[i].y);
  	}
  	glEnd();
  }
  
  void DebugDraw::DrawSolidPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color)
  {
  	glEnable(GL_BLEND);
  	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  	glColor4f(0.5f * color.r, 0.5f * color.g, 0.5f * color.b, 0.5f);
  	glBegin(GL_TRIANGLE_FAN);
  	for (int32 i = 0; i < vertexCount; ++i)
  	{
  		glVertex2f(vertices[i].x, vertices[i].y);
  	}
  	glEnd();
  	glDisable(GL_BLEND);
  
  	glColor4f(color.r, color.g, color.b, 1.0f);
  	glBegin(GL_LINE_LOOP);
  	for (int32 i = 0; i < vertexCount; ++i)
  	{
  		glVertex2f(vertices[i].x, vertices[i].y);
  	}
  	glEnd();
  }
  
  void DebugDraw::DrawCircle(const b2Vec2& center, float32 radius, const b2Color& color)
  {
  	const float32 k_segments = 16.0f;
  	const float32 k_increment = 2.0f * b2_pi / k_segments;
  	float32 theta = 0.0f;
  	glColor3f(color.r, color.g, color.b);
  	glBegin(GL_LINE_LOOP);
  	for (int32 i = 0; i < k_segments; ++i)
  	{
  		b2Vec2 v = center + radius * b2Vec2(cosf(theta), sinf(theta));
  		glVertex2f(v.x, v.y);
  		theta += k_increment;
  	}
  	glEnd();
  }
  
  void DebugDraw::DrawSolidCircle(const b2Vec2& center, float32 radius, const b2Vec2& axis, const b2Color& color)
  {
  	const float32 k_segments = 16.0f;
  	const float32 k_increment = 2.0f * b2_pi / k_segments;
  	float32 theta = 0.0f;
  	glEnable(GL_BLEND);
  	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  	glColor4f(0.5f * color.r, 0.5f * color.g, 0.5f * color.b, 0.5f);
  	glBegin(GL_TRIANGLE_FAN);
  	for (int32 i = 0; i < k_segments; ++i)
  	{
  		b2Vec2 v = center + radius * b2Vec2(cosf(theta), sinf(theta));
  		glVertex2f(v.x, v.y);
  		theta += k_increment;
  	}
  	glEnd();
  	glDisable(GL_BLEND);
  
  	theta = 0.0f;
  	glColor4f(color.r, color.g, color.b, 1.0f);
  	glBegin(GL_LINE_LOOP);
  	for (int32 i = 0; i < k_segments; ++i)
  	{
  		b2Vec2 v = center + radius * b2Vec2(cosf(theta), sinf(theta));
  		glVertex2f(v.x, v.y);
  		theta += k_increment;
  	}
  	glEnd();
  
  	b2Vec2 p = center + radius * axis;
  	glBegin(GL_LINES);
  	glVertex2f(center.x, center.y);
  	glVertex2f(p.x, p.y);
  	glEnd();
  }
  
  void DebugDraw::DrawSegment(const b2Vec2& p1, const b2Vec2& p2, const b2Color& color)
  {
  	glColor3f(color.r, color.g, color.b);
  	glBegin(GL_LINES);
  	glVertex2f(p1.x, p1.y);
  	glVertex2f(p2.x, p2.y);
  	glEnd();
  }
  
  void DebugDraw::DrawXForm(const b2XForm& xf)
  {
  	b2Vec2 p1 = xf.position, p2;
  	const float32 k_axisScale = 0.4f;
  	glBegin(GL_LINES);
  	
  	glColor3f(1.0f, 0.0f, 0.0f);
  	glVertex2f(p1.x, p1.y);
  	p2 = p1 + k_axisScale * xf.R.col1;
  	glVertex2f(p2.x, p2.y);
  
  	glColor3f(0.0f, 1.0f, 0.0f);
  	glVertex2f(p1.x, p1.y);
  	p2 = p1 + k_axisScale * xf.R.col2;
  	glVertex2f(p2.x, p2.y);
  
  	glEnd();
  }
  
  void DebugDraw::DrawPoint(const b2Vec2& p, float32 size, const b2Color& color)
  {
  	glPointSize(size);
  	glBegin(GL_POINTS);
  	glColor3f(color.r, color.g, color.b);
  	glVertex2f(p.x, p.y);
  	glEnd();
  	glPointSize(1.0f);
  }
  
  void DebugDraw::DrawString(int x, int y, const char *string, ...)
  {
  	char buffer[128];
  
  	va_list arg;
  	va_start(arg, string);
  	vsprintf(buffer, string, arg);
  	va_end(arg);
  
  	glMatrixMode(GL_PROJECTION);
  	glPushMatrix();
  	glLoadIdentity();
  	int w = glutGet(GLUT_WINDOW_WIDTH);
  	int h = glutGet(GLUT_WINDOW_HEIGHT);
  	gluOrtho2D(0, w, h, 0);
  	glMatrixMode(GL_MODELVIEW);
  	glPushMatrix();
  	glLoadIdentity();
  
  	glColor3f(0.9f, 0.6f, 0.6f);
  	glRasterPos2i(x, y);
  	int32 length = (int32)strlen(buffer);
  	for (int32 i = 0; i < length; ++i)
  	{
  		glutBitmapCharacter(GLUT_BITMAP_8_BY_13, buffer[i]);
  	}
  
  	glPopMatrix();
  	glMatrixMode(GL_PROJECTION);
  	glPopMatrix();
  	glMatrixMode(GL_MODELVIEW);
  }
  
  void DebugDraw::DrawAABB(b2AABB* aabb, const b2Color& c)
  {
  	glColor3f(c.r, c.g, c.b);
  	glBegin(GL_LINE_LOOP);
  	glVertex2f(aabb->lowerBound.x, aabb->lowerBound.y);
  	glVertex2f(aabb->upperBound.x, aabb->lowerBound.y);
  	glVertex2f(aabb->upperBound.x, aabb->upperBound.y);
  	glVertex2f(aabb->lowerBound.x, aabb->upperBound.y);
  	glEnd();
  }
  