Redline/source/stencil.cpp

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C++
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//stencil.cpp
//draw a covering plane whereever stencil values are !=0, to simulate shadow and light volumes
#include <OpenGL/gl.h>
#include "vectors.h"
#include "environment.h"
#include "screen.h"
#include "gamemem.h"
#include "config.h"
float gStencilZoom=1.0;
//draw a covering plane whereever stencil values are !=0
//if shadow is true draw using shadow color to simulate shadow volumes
//else draw using spotlight color to simulate light cones.
void RenderStencilLayer(int shadow,int stencil)
{
if(!stencil)
return;
glPushAttrib(GL_DEPTH_BUFFER_BIT+GL_LIGHTING_BIT+GL_COLOR_BUFFER_BIT+GL_TEXTURE_BIT+GL_CURRENT_BIT+GL_STENCIL_BUFFER_BIT);
GLfloat shadowColor[4];
if(shadow)
{
*(tVector3*)shadowColor=gEnvironment->shadowColor;
shadowColor[3]=gEnvironment->shadowIntensity;
shadowColor[3]/=stencil;
}
else
{
*(tVector3*)shadowColor=gEnvironment->spotLightColor*(1/(stencil*1.5));
shadowColor[3]=1;
}
glColor4fv(shadowColor);
glDisable(GL_LIGHTING);
glDisable(GL_TEXTURE_2D);
glDisable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_NOTEQUAL, 1, 0xffffffff);
glStencilOp(GL_KEEP, GL_REPLACE, GL_REPLACE);
if(shadow)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
else
glBlendFunc(GL_DST_COLOR, GL_ONE);
glLoadIdentity();
glBegin(GL_TRIANGLE_STRIP);
glVertex3f(-2.0f, 1.0f,-1.00f);
glVertex3f(-2.0f,-1.0f,-1.00f);
glVertex3f( 2.0f, 1.0f,-1.00f);
glVertex3f( 2.0f,-1.0f,-1.00f);
glEnd();
glPopAttrib();
}