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knight666

OpenGL Shadow mapping using shaders

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Hello, for the past week or so I've been trying to get shadow mapping to work, without much success. I'll get right to it and post the relevant bits of my code. It's a huge mess but it doesn't work yet.
#define CGLE() \	
{

	int error_codez2 = glGetError(); \
	if (error_codez2 > 0) \	{ \
		ERROR_OPENGL("%s (Error code: %i) at line %i in file %s.", gluErrorString(error_codez2), error_codez2, __LINE__, __FILE__); \
		
	} \
}

void Engine::Init()
{
	glGenBuffersARB				= (PFNGLGENBUFFERSARBPROC)				wglGetProcAddress("glGenBuffersARB");
	glBindBufferARB				= (PFNGLBINDBUFFERARBPROC)				wglGetProcAddress("glBindBufferARB");
	glBufferDataARB				= (PFNGLBUFFERDATAARBPROC)				wglGetProcAddress("glBufferDataARB");
	glBufferSubDataARB			= (PFNGLBUFFERSUBDATAARBPROC)			wglGetProcAddress("glBufferSubDataARB");
	glDeleteBuffersARB			= (PFNGLDELETEBUFFERSARBPROC)			wglGetProcAddress("glDeleteBuffersARB");

	// shadows

	glGenTextures(1, &s_ShadowTexture); CGLE();
	glBindTexture(GL_TEXTURE_2D, s_ShadowTexture); CGLE();
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); CGLE();
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); CGLE();
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); CGLE();
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); CGLE();

	// enable shadow comparison
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE_ARB, GL_COMPARE_R_TO_TEXTURE_ARB); CGLE();

	// if r <= texture
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL); CGLE();

	// return an intensity
	glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_INTENSITY); CGLE();

	const GLdouble x[] = {1.0, 0.0, 0.0, 0.0};
	const GLdouble y[] = {0.0, 1.0, 0.0, 0.0};
	const GLdouble z[] = {0.0, 0.0, 1.0, 0.0};
	const GLdouble w[] = {0.0, 0.0, 0.0, 1.0};

	glEnable(GL_TEXTURE_GEN_S); CGLE();
	glEnable(GL_TEXTURE_GEN_T); CGLE();
	glEnable(GL_TEXTURE_GEN_R); CGLE();
	glEnable(GL_TEXTURE_GEN_Q); CGLE();

	glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); CGLE();
	glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); CGLE();
	glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); CGLE();
	glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); CGLE();

	glTexGendv(GL_S, GL_EYE_PLANE, x); CGLE();
	glTexGendv(GL_T, GL_EYE_PLANE, y); CGLE();
	glTexGendv(GL_R, GL_EYE_PLANE, z); CGLE();
	glTexGendv(GL_Q, GL_EYE_PLANE, w); CGLE();

	glTexImage2D (
		GL_TEXTURE_2D,			// target
		0,						// level
		GL_DEPTH_COMPONENT,		// internal format
		g_ShadowWidth,			// width
		g_ShadowHeight,			// height
		0,						// border
		GL_DEPTH_COMPONENT,		// format
		GL_UNSIGNED_BYTE,		// type
		NULL					// pixels
	); CGLE();
	glBindTexture(GL_TEXTURE_2D, 0); CGLE();
}

void Engine::GenerateShadows()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); CGLE();

	float pos[4] = { s_Lights[0]->GetPosition().x, s_Lights[0]->GetPosition().y, s_Lights[0]->GetPosition().z, 0 };

	glMatrixMode(GL_PROJECTION); CGLE();
	glLoadIdentity(); CGLE();
	gluPerspective(g_SpotAngle, 1.f, g_ShadowNear, g_ShadowFar); CGLE();
	glGetFloatv(GL_MODELVIEW_MATRIX, g_LightProjectionMatrix); CGLE();

	glMatrixMode(GL_MODELVIEW); CGLE();
	glLoadIdentity(); CGLE();
	gluLookAt (
		pos[0], pos[1], pos[2],
		0, 0, 0,
		0, 1, 0
	); CGLE();
	glGetFloatv(GL_MODELVIEW_MATRIX, g_LightModelMatrix); CGLE();

	float cam[16];

	glPushMatrix(); CGLE();
		glMatrixMode(GL_MODELVIEW); CGLE();
		glLoadIdentity(); CGLE();
		Project(); CGLE();
		glGetFloatv(GL_MODELVIEW_MATRIX, cam); CGLE();
	glPopMatrix(); CGLE();

	g_InverseCamera[0] = cam[0]; 
	g_InverseCamera[1] = cam[4]; 
	g_InverseCamera[2] = cam[8];
	g_InverseCamera[3] = 0.0f; 

	g_InverseCamera[4] = cam[1]; 
	g_InverseCamera[5] = cam[5]; 
	g_InverseCamera[6] = cam[9];
	g_InverseCamera[7] = 0.0f; 

	g_InverseCamera[8] = cam[2]; 
	g_InverseCamera[9] = cam[6]; 
	g_InverseCamera[10] = cam[10];
	g_InverseCamera[11] = 0.0f;

	g_InverseCamera[12] = 
		-(cam[12] * cam[0]) - 
		(cam[13] * cam[1]) - 
		(cam[14] * cam[2]);

	g_InverseCamera[13] = 
		-(cam[12] * cam[4]) - 
		(cam[13] * cam[5]) - 
		(cam[14] * cam[6]);

	g_InverseCamera[14] = 
		-(cam[12] * cam[8]) - 
		(cam[13] * cam[9]) - 
		(cam[14] * cam[10]);

	g_InverseCamera[15] = 1.0f;

	/*g_InverseCamera[0] = g_LightProjectionMatrix[0]; 
	g_InverseCamera[1] = g_LightProjectionMatrix[4]; 
	g_InverseCamera[2] = g_LightProjectionMatrix[8];

	g_InverseCamera[4] = g_LightProjectionMatrix[1]; 
	g_InverseCamera[5] = g_LightProjectionMatrix[5]; 
	g_InverseCamera[6] = g_LightProjectionMatrix[9];

	g_InverseCamera[8] = g_LightProjectionMatrix[2]; 
	g_InverseCamera[9] = g_LightProjectionMatrix[6]; 
	g_InverseCamera[10] = g_LightProjectionMatrix[10];

	g_InverseCamera[3] = 0.0f; 
	g_InverseCamera[7] = 0.0f; 
	g_InverseCamera[11] = 0.0f;
	g_InverseCamera[15] = 1.0f;

	g_InverseCamera[12] = 
		-(g_LightProjectionMatrix[12] * g_LightProjectionMatrix[0]) - 
		(g_LightProjectionMatrix[13] * g_LightProjectionMatrix[1]) - 
		(g_LightProjectionMatrix[14] * g_LightProjectionMatrix[2]);

	g_InverseCamera[13] = 
		-(g_LightProjectionMatrix[12] * g_LightProjectionMatrix[4]) - 
		(g_LightProjectionMatrix[13] * g_LightProjectionMatrix[5]) - 
		(g_LightProjectionMatrix[14] * g_LightProjectionMatrix[6]);

	g_InverseCamera[14] = 
		-(g_LightProjectionMatrix[12] * g_LightProjectionMatrix[8]) - 
		(g_LightProjectionMatrix[13] * g_LightProjectionMatrix[9]) - 
		(g_LightProjectionMatrix[14] * g_LightProjectionMatrix[10]);*/

	glActiveTextureARB(GL_TEXTURE7); CGLE();
	glMatrixMode(GL_TEXTURE); CGLE();
	glLoadIdentity(); CGLE();
	glLoadMatrixf(g_ShadowBias); CGLE();
	glMultMatrixf(g_LightProjectionMatrix); CGLE();
	glMultMatrixf(g_LightModelMatrix); CGLE();
	glMultMatrixf(g_InverseCamera); CGLE();
	glMatrixMode(GL_MODELVIEW);

	glViewport (
		0, 0, 
		g_ShadowWidth, g_ShadowHeight
	); CGLE();

	if (!check_shadow)
	{
		glEnable(GL_CULL_FACE); CGLE();
		glCullFace(GL_FRONT); CGLE();
		glDisable(GL_LIGHTING); CGLE();
		glShadeModel(GL_FLAT); CGLE();
		glDisable(GL_TEXTURE_2D); CGLE();
		glEnable(GL_POLYGON_OFFSET_FILL); CGLE();
		glColorMask(0, 0, 0, 0); CGLE();
	}

	// first pass
	s_Game->Render(check_shadow);

	glEnable(GL_TEXTURE_2D); CGLE();

	glBindTexture(GL_TEXTURE_2D, s_ShadowTexture); CGLE();
	glCopyTexSubImage2D (
		GL_TEXTURE_2D,		// target
		0,					// level
		0,					// x offset
		0,					// y offset	
		0,					// x
		0,					// y
		g_ShadowWidth,		// width
		g_ShadowHeight		// height
	); CGLE();

	if (!check_shadow)
	{
		glColorMask(1, 1, 1, 1); CGLE();
		glDisable(GL_POLYGON_OFFSET_FILL); CGLE();
		glShadeModel(GL_SMOOTH); CGLE();
		glEnable(GL_LIGHTING); CGLE();
		glCullFace(GL_BACK); CGLE();
		glDisable(GL_CULL_FACE); CGLE();
		glEnable(GL_DEPTH_TEST); CGLE();
	}

	glDisable(GL_TEXTURE_2D); CGLE();

	glMatrixMode(GL_TEXTURE); CGLE();
	glLoadIdentity(); CGLE();
	
	if (!check_shadow)
	{
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); CGLE();
	}
}

void Engine::PreRender()
{
	// clear the screen
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	s_Game->PreRender();
}

void Engine::Render()
{
	if (check_shadow)
	{
		GenerateShadows();
		glutSwapBuffers();
	}
	else
	{
		GenerateShadows();
		
		glViewport (
			0, 0, 
			Window::GetWidth(), Window::GetHeight()
		); CGLE();

		glMatrixMode(GL_PROJECTION); CGLE();
		glLoadIdentity(); CGLE();
		gluPerspective (
			s_FOV, 
			(float)Window::GetWidth() / (float)Window::GetHeight(), 
			s_ZNear, s_ZFar
		); CGLE();
		glGetFloatv(GL_MODELVIEW_MATRIX, g_ProjectionMatrix); CGLE();

		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity(); CGLE();
		Project();
		glGetFloatv(GL_MODELVIEW_MATRIX, g_ModelMatrix); CGLE();

		glActiveTextureARB(GL_TEXTURE6); CGLE();
		glMatrixMode(GL_TEXTURE); CGLE();
		glLoadIdentity(); CGLE();
		glLoadMatrixf(g_ModelMatrix); CGLE();
		glMultMatrixf(g_ProjectionMatrix); CGLE();
		//glRotatef(30.f, 0, 1, 0);
		glMatrixMode(GL_MODELVIEW);

		SwitchPerspective(Window::GetWidth(), Window::GetHeight());
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity(); CGLE();
		Project();

		PreRender();

			glEnable(GL_LIGHTING); CGLE();

			// lights
			for (std::vector<Light*>::iterator i = s_Lights.begin(); i != s_Lights.end(); ++i)
			{
				float pos[4] = { (*i)->GetPosition().x, (*i)->GetPosition().y, (*i)->GetPosition().z, 0 };

				int options = (*i)->GetOptions();

				glLightfv(GL_LIGHT0, GL_POSITION, pos); CGLE();
				if (options & LIGHT_AMBIENT)	{ glLightfv(GL_LIGHT0, GL_AMBIENT, (*i)->GetAmbient().GetOpenGLColor()); CGLE(); }
				if (options & LIGHT_DIFFUSE)	{ glLightfv(GL_LIGHT0, GL_DIFFUSE, (*i)->GetDiffuse().GetOpenGLColor()); CGLE(); }
				if (options & LIGHT_SPECULAR)	{ glLightfv(GL_LIGHT0, GL_SPECULAR, (*i)->GetSpecular().GetOpenGLColor()); CGLE(); } 
			}

			s_Game->Render();

		PostRender();
	}
}

void Engine::PostRender()
{
	s_Game->PostRender();

	// set up the camera
	glLoadIdentity(); CGLE();
	Project();

	// draw everything and swap the display buffer
	glutSwapBuffers(); CGLE();
}

void Engine::Project()
{
	s_Game->m_CurrentCam->Project();
}
So this code takes the matrix from the perspective of the light and multiplies it with the inverse of the eye camera. That way we get some nice values to use for the following shader: Lighting.vert
varying vec3 normal;
varying vec3 to_light;
varying vec3 eye;
varying vec3 pos;

varying vec4 shadow_coord;

attribute vec3 vTangent;

void main()
{
    // triangle
	
    normal = normalize(gl_NormalMatrix * gl_Normal);	
    vec3 tangent = normalize(gl_NormalMatrix * vec3(0, 1, 0));
    vec3 binormal = cross(normal, tangent);
	
    pos = vec3(gl_ModelViewMatrix * gl_Vertex);

    vec3 light_pos = vec3(gl_LightSource[0].position) - pos;
	
    to_light.x = dot(light_pos, tangent);
    to_light.y = dot(light_pos, binormal);
    to_light.z = dot(light_pos, normal);

    vec3 temp = -pos;
    eye.x = dot(temp, tangent);
    eye.y = dot(temp, binormal);
    eye.z = dot(temp, normal);
	
    mat4 matCam = gl_TextureMatrix[6];
    mat4 matModel = gl_TextureMatrix[5];
    mat4 matShadow = gl_TextureMatrix[7];

    // texturing
    gl_TexCoord[0] = gl_MultiTexCoord0;
	
    // camera
    gl_TexCoord[1] = gl_ModelViewMatrix * gl_Vertex;
    
    // shadow
    shadow_coord = matShadow * gl_ModelViewMatrix * gl_Vertex;	

    gl_Position = gl_ModelViewProjectionMatrix * matModel * gl_Vertex;
}
Lighting.frag
varying vec3 normal;
varying vec3 to_light;
varying vec3 eye;
varying vec3 pos;
varying vec4 shadow_coord;

uniform sampler2D tex_diffuse;
uniform sampler2D tex_specular;
uniform sampler2D tex_bump;
uniform sampler2D tex_alphakey;

uniform sampler2DShadow tex_shadows;

varying vec3 N, L, E, R;
varying float lambert;
varying vec2 uv;

varying vec4 final;

vec4 TexturingAlpha()
{
	vec4 result;

	vec4 texel_color = texture2D(tex_diffuse, uv);
	vec4 texel_alpha = texture2D(tex_alphakey, uv);

	result = texel_color * final;
	
	if (texel_alpha.a != 0.0)
	{
		float mask = (texel_alpha.r + texel_alpha.g + texel_alpha.b) / 3.0;
		result.a = mask;
	}
	
	return result;
}

void main()
{	
	uv = gl_TexCoord[0].st;
	
	N = normal;
	L = normalize(gl_LightSource[0].position.xyz);
	E = normalize(-pos);
	
	float dist = length(normalize(gl_LightSource[0].position.xyz - pos));
	float atten = 1.0 / (
		gl_LightSource[0].constantAttenuation + 
		gl_LightSource[0].linearAttenuation * dist +
		gl_LightSource[0].quadraticAttenuation * dist * dist
	);

	// ambient term
	vec4 ambient = (gl_LightSource[0].ambient * gl_FrontMaterial.ambient);
	
	// diffuse term
	vec4 diffuse = vec4(0.0, 0.0, 0.0, 1.0);
	
	// specular term
	vec4 specular = vec4(0.0, 0.0, 0.0, 1.0);
	
	final = ambient + (atten * gl_FrontMaterial.ambient);
	
	lambert = dot(N, L);
	if (lambert > 0.0)
	{
		final += gl_LightSource[0].diffuse * gl_FrontMaterial.diffuse * lambert * atten;
		
		float shiny = normalize(-reflect(L, N));
		float shiny2 = dot(shiny, E);
		if (shiny2 > 0.0)
		{
			float amount = pow(shiny2, gl_FrontMaterial.shininess);
			final += gl_LightSource[0].specular * gl_FrontMaterial.specular * amount * atten;
		}
	}
	
	vec4 shadow_color = vec4(0.0, 0.0, 0.0, 1.0);
	float shadowness = shadow2DProj(tex_shadows, shadow_coord).r;
	shadowness = clamp(shadowness, 0.0, 1.0);
	
	vec3 coord_pos = shadow_coord.xyz / shadow_coord.w;
	
	if (coord_pos.x >= 0.0 && coord_pos.y >= 0.0 && coord_pos.x <= 10.0 && coord_pos.y <= 10.0)
	{
		shadow_color.rgb = TexturingAlpha() * shadowness * final.rgb;
		gl_FragColor = shadow_color;
	}
	else
	{
		gl_FragColor = final;
	}
}
However, this code does not do what I want it to do. It does something like this: http://imgur.com/CHKHx.png (I apologize to future Googlers if the link is no longer available. Imagine a complex scene shaded in red, except for a square in the middle that is textured) Instead of checking if something is in the shade, it renders a nice light blob in front of everything. How can I fix my shadow mapping? Thanks in advance. [Edited by - knight666 on April 4, 2010 3:37:44 AM]

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Are you rendering the depth buffer to the shadowmap correctly? instead of glCopyTexSubImage2D maybe consider using Framebuffer objects like this.

in init()
// Generate shadow map Texture
glGenTextures(1, &shadowMap);
glBindTexture(GL_TEXTURE_2D, shadowMap);
glTexImage2D( GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32, shadowMapSize, shadowMapSize, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri( GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_INTENSITY);
glBindTexture(GL_TEXTURE_2D, 0);

// Create FBO
glGenFramebuffersEXT(1,&frameBufferShadow);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, frameBufferShadow);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,GL_TEXTURE_2D, shadowMap, 0);

// check FBO status
GLenum FBOstatus = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
if(FBOstatus != GL_FRAMEBUFFER_COMPLETE_EXT)
printf("GL_FRAMEBUFFER_COMPLETE failed, CANNOT use FBO\n");

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);




and this during render, with camera set to lights view

void Game::CreateShadowMap(){
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, frameBufferShadow);

glClear(GL_DEPTH_BUFFER_BIT);

glPushAttrib( GL_VIEWPORT_BIT );
glViewport( 0, 0, shadowMapSize, shadowMapSize );
scene.DrawShadowMap(); //draws scene, unlit and untextured
glPopAttrib();

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,0);
}




I suggest rendering the shadow map to a textured quad to make sure it worked.

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I now render my depth to a framebuffer. I put it on the screen like this:

	if (check_shadow)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); CGLE();

glDisable(GL_LIGHTING);

glViewport(0, 0, Window::GetWidth(), Window::GetHeight());

glMatrixMode(GL_TEXTURE);
glLoadIdentity();

glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, s_ShadowTexture);
//glBindTexture(GL_TEXTURE_2D, g_TestTexture->GetID());

glMatrixMode(GL_MODELVIEW);
glPushMatrix();
{
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glPushMatrix();
{
glLoadIdentity ();
glBegin(GL_QUADS);
{
glVertex3f(-1.0f, -1.0f, 0.0f); glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); glTexCoord2f(0.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, 0.0f); glTexCoord2f(1.0f, 0.0f);
}
glEnd();
}
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
glPopMatrix();

glEnable(GL_LIGHTING);
glDisable(GL_TEXTURE_2D);
}


I've verified with another texture that it works, but I get a beautiful white screen. :(

[Edited by - knight666 on April 4, 2010 3:19:57 AM]

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Try setting the GL_TEXTURE_COMPARE_MODE attribute of your depth texture to GL_NONE (might be by default, not sure. god, i _really_ have to check that some day). Also perhaps set the GL_DEPTH_TEXTURE_MODE attribute of your depth texture to GL_INTENSITY. Just to be sure :)
Note that depth 'colors' rendered using central projection may end up being very close to 1 - thus white - especially if you're using a larger depth range. What are the actual values of g_shadowNear and g_shadowFar?


Here's a version you could try:
Important note: you should call glTexCoord2f() _before_ calling glVertex3f(). glVertex...() finishes vertex definition and moves to the next vertex. Still you would most likely have ended up with a distorted but visible image. Plain white indicates some of the above things :)

	if (check_shadow)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); CGLE();

glDisable(GL_LIGHTING);

glViewport(0, 0, Window::GetWidth(), Window::GetHeight());

glMatrixMode(GL_TEXTURE);
glLoadIdentity();

glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, s_ShadowTexture);

//insert texture attributes here or during texture construction, whichever you prefer:
glTexParameteri(GL_TEXTURE_2D,GL_DEPTH_TEXTURE_MODE,GL_INTENSITY);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_COMPARE_MODE,GL_NONE);

glMatrixMode(GL_MODELVIEW);
glPushMatrix();
{
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glPushMatrix();
{
glLoadIdentity ();
glBegin(GL_QUADS);
{
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f(1.0f, 1.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f(1.0f, -1.0f, 0.0f);
}
glEnd();
}
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
glPopMatrix();

glEnable(GL_LIGHTING);
glDisable(GL_TEXTURE_2D);
}


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If I use those modes, I indeed get a depth texture. :D

Especially when I use these values:

float g_ShadowNear = 10.f;
float g_ShadowFar = 40000.f;



Instead of these:

float g_ShadowNear = 0.5f;
float g_ShadowFar = 25.f;



However, my shadows still don't get calculated properly. I still end up with a light blob somewhere.

[Edited by - knight666 on April 4, 2010 7:09:35 AM]

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I would advise against using shadow2DProj in your shader, instead do something like this.

Vertex

varying vec4 shadowTexCoord;

void main() {
shadowTexCoord = gl_TextureMatrix[7]*gl_ModelViewMatrix*gl_Vertex;
}








where the gl_TextureMatrix[7] is the ProjectionLight*ModelViewLight*ModelViewCameraInverse

The inverse might be hard to get, I used a class from the Game Programming Gems 1 CD.

Fragment

uniform sampler2D shadowMap;
varying vec4 shadowTexCoord;
void main() {
vec3 shadowPersp = shadowTexCoord.xyz/shadowTexCoord.w; // probably not neccisary for ortho.
float depth = texture2D(shadowMap,shadowPersp.xy).r;
float shadow=1.0;

if (depth+0.001<shadowPersp.z && shadowPersp.x>0.0 && shadowPersp.x<1.0 && shadowPersp.y>0.0 && shadowPersp.y<1.0)
shadow=0.0;








Setting up Light Matrix for shader.


glMatrixMode(GL_TEXTURE);
glMatrixMode(GL_TEXTURE);
glActiveTextureARB(GL_TEXTURE7);
glLoadIdentity(); // clear things up
glTranslated(0.5, 0.5, 0.5); // we have to clamp values in the [0.0, 1.0] range, not [-1.0, 1.0]
glScaled(0.5, 0.5, 0.5);
glMultMatrixf(lightProjMatrix); // now multiply by the matrices we have retrieved before
glMultMatrixf(lightMVMatrix);
float curMV[16];
glGetFloatv(GL_MODELVIEW_MATRIX, curMV);
matrix44 inverseMV;
inverseMV.col[0].x=curMV[0];inverseMV.col[0].y=curMV[1];inverseMV.col[0].z=curMV[2];inverseMV.col[0].w=curMV[3];
inverseMV.col[1].x=curMV[4];inverseMV.col[1].y=curMV[5];inverseMV.col[1].z=curMV[6];inverseMV.col[1].w=curMV[7];
inverseMV.col[2].x=curMV[8];inverseMV.col[2].y=curMV[9];inverseMV.col[2].z=curMV[10];inverseMV.col[2].w=curMV[11];
inverseMV.col[3].x=curMV[12];inverseMV.col[3].y=curMV[13];inverseMV.col[3].z=curMV[14];inverseMV.col[3].w=curMV[15];
inverseMV.invert();
curMV[0]=inverseMV.col[0].x;curMV[1]=inverseMV.col[0].y;curMV[2]=inverseMV.col[0].z;curMV[3]=inverseMV.col[0].w;
curMV[4]=inverseMV.col[1].x;curMV[5]=inverseMV.col[1].y;curMV[6]=inverseMV.col[1].z;curMV[7]=inverseMV.col[1].w;
curMV[8]=inverseMV.col[2].x;curMV[9]=inverseMV.col[2].y;curMV[10]=inverseMV.col[2].z;curMV[11]=inverseMV.col[2].w;
curMV[12]=inverseMV.col[3].x;curMV[13]=inverseMV.col[3].y;curMV[14]=inverseMV.col[3].z;curMV[15]=inverseMV.col[3].w;
glMultMatrixf(curMV);
glMatrixMode(GL_MODELVIEW);




[Edited by - Argo15 on April 4, 2010 10:46:21 AM]

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I've implemented it and this is my result: a tiny black square indicating my shadow, only it is dependent on the camera.

http://imgur.com/lIJ3T.png

Here is my codez for gl_TextureMatrix[7]:

glMatrixMode(GL_TEXTURE); CGLE();
glActiveTextureARB(GL_TEXTURE7); CGLE();
glLoadIdentity(); CGLE();
//glLoadMatrixf(g_ShadowBias); CGLE();

glScaled(0.5, 0.5, 0.5);
glTranslated(0.5, 0.5, 0.5);

glMultMatrixf(g_LightProjectionMatrix); CGLE();
glMultMatrixf(g_LightModelMatrix); CGLE();

float cam[16];

glGetFloatv(GL_MODELVIEW_MATRIX, cam);

g_InverseCamera[0] = cam[0];
g_InverseCamera[1] = cam[4];
g_InverseCamera[2] = cam[8];
g_InverseCamera[3] = 0.0f;

g_InverseCamera[4] = cam[1];
g_InverseCamera[5] = cam[5];
g_InverseCamera[6] = cam[9];
g_InverseCamera[7] = 0.0f;

g_InverseCamera[8] = cam[2];
g_InverseCamera[9] = cam[6];
g_InverseCamera[10] = cam[10];
g_InverseCamera[11] = 0.0f;

g_InverseCamera[12] =
-(cam[12] * cam[0]) -
(cam[13] * cam[1]) -
(cam[14] * cam[2]);

g_InverseCamera[13] =
-(cam[12] * cam[4]) -
(cam[13] * cam[5]) -
(cam[14] * cam[6]);

g_InverseCamera[14] =
-(cam[12] * cam[8]) -
(cam[13] * cam[9]) -
(cam[14] * cam[10]);

g_InverseCamera[15] = 1.0f;

glMultMatrixf(g_InverseCamera); CGLE();
//glMultMatrixf(cam); CGLE();

glMatrixMode(GL_MODELVIEW);



Here is my vertex shader:

	
varying vec3 normal;
varying vec3 to_light;
varying vec3 eye;
varying vec3 pos;

varying vec4 shadow_coord;

attribute vec3 vTangent;

void main()
{
// triangle

normal = normalize(gl_NormalMatrix * gl_Normal);
vec3 tangent = normalize(gl_NormalMatrix * vec3(0, 1, 0));
vec3 binormal = cross(normal, tangent);

pos = vec3(gl_ModelViewMatrix * gl_Vertex);

vec3 light_pos = vec3(gl_LightSource[0].position) - pos;

// to_light = -light_pos;
to_light.x = dot(light_pos, tangent);
to_light.y = dot(light_pos, binormal);
to_light.z = dot(light_pos, normal);

//eye = -pos;
vec3 temp = -pos;
eye.x = dot(temp, tangent);
eye.y = dot(temp, binormal);
eye.z = dot(temp, normal);

// texturing
gl_TexCoord[0] = gl_MultiTexCoord0;

mat4 matCam = gl_TextureMatrix[6];
mat4 matModel = gl_TextureMatrix[5];
mat4 matShadow = gl_TextureMatrix[7];

shadow_coord = matShadow * gl_ModelViewMatrix * gl_Vertex;

gl_Position = gl_ModelViewProjectionMatrix * matModel * gl_Vertex;
}


And the fragment shader:

varying vec3 normal;
varying vec3 to_light;
varying vec3 eye;
varying vec3 pos;
varying vec4 shadow_coord;

uniform sampler2D tex_diffuse;
uniform sampler2D tex_specular;
uniform sampler2D tex_bump;
uniform sampler2D tex_alphakey;

uniform sampler2D tex_shadows;
//uniform sampler2DShadow tex_shadows;

vec3 N, L, E, R;
float lambert;
vec2 uv;

varying vec4 final;

void main()
{
uv = gl_TexCoord[0].st;

N = normalize(normal);
L = normalize(gl_LightSource[0].position.xyz);
E = normalize(-pos);

float dist = length(normalize(gl_LightSource[0].position.xyz - pos));
float atten = 1.0 / (
gl_LightSource[0].constantAttenuation +
gl_LightSource[0].linearAttenuation * dist +
gl_LightSource[0].quadraticAttenuation * dist * dist
);

// ambient term
vec4 ambient = (gl_LightSource[0].ambient * gl_FrontMaterial.ambient);

// diffuse term
vec4 diffuse = vec4(0.0, 0.0, 0.0, 1.0);

// specular term
vec4 specular = vec4(0.0, 0.0, 0.0, 1.0);

final = ambient + (atten * gl_FrontMaterial.ambient);

lambert = dot(N, L);
if (lambert > 0.0)
{
final += gl_LightSource[0].diffuse * gl_FrontMaterial.diffuse * lambert * atten;

vec3 shiny = normalize(-reflect(L, N));
float shiny2 = dot(shiny, E);
if (shiny2 > 0.0)
{
float amount = pow(shiny2, gl_FrontMaterial.shininess);
final += gl_LightSource[0].specular * gl_FrontMaterial.specular * amount * atten;
}
}

vec4 shadow_color = vec4(0.0, 0.0, 0.0, 1.0);

vec3 shadow_perspective = shadow_coord.xyz / shadow_coord.w;

float depth = texture2D(tex_shadows, shadow_perspective.xy).r;
float shadow = 1.0;
float alpha = 1.0;

if (
depth + 0.001 < shadow_perspective.z &&
shadow_perspective.x > 0.0 &&
shadow_perspective.x < 1.0 &&
shadow_perspective.y > 0.0 &&
shadow_perspective.y < 1.0
)
{
shadow = 0.0;
alpha = 1.0;
}
else
{
shadow = 1.0;
}

shadow_color = TexturingAlpha() * shadow * final;

if (shadow == 1.0)
{
alpha = shadow_color.a;
}

gl_FragColor.rgb = shadow_color.rgb;
gl_FragColor.a = alpha;
}

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I'm not sure if you correctly found the inverse to the camera (idk I might be wrong I'm still fairly new to linear algebra =P), I'll post the inverse code i used.


class matrix44
{
public:
vector4 col[4];

matrix44() {};
~matrix44() {};

matrix44 &invert();
}






// Invert the matrix44
matrix44 &matrix44::invert()
{
matrix44 a(*this);
matrix44 b(IdentityMatrix44());

unsigned int r, c;
unsigned int cc;
unsigned int rowMax; // Points to max abs value row in this column
unsigned int row;
float tmp;

// Go through columns
for (c=0; c<4; c++)
{

// Find the row with max value in this column
rowMax = c;
for (r=c+1; r<4; r++)
{
if (fabs(a[c][r]) > fabs(a[c][rowMax]))
{
rowMax = r;
}
}

// Swap row "rowMax" with row "c"
for (cc=0; cc<4; cc++)
{
tmp = a[cc][c];
a[cc][c] = a[cc][rowMax];
a[cc][rowMax] = tmp;
tmp = b[cc][c];
b[cc][c] = b[cc][rowMax];
b[cc][rowMax] = tmp;
}

// Now everything we do is on row "c".
// Set the max cell to 1 by dividing the entire row by that value
tmp = a[c][c];
for (cc=0; cc<4; cc++)
{
a[cc][c] /= tmp;
b[cc][c] /= tmp;
}

// Now do the other rows, so that this column only has a 1 and 0's
for (row = 0; row < 4; row++)
{
if (row != c)
{
tmp = a[c][row];
for (cc=0; cc<4; cc++)
{
a[cc][row] -= a[cc][c] * tmp;
b[cc][row] -= b[cc][c] * tmp;
}
}
}

}

*this = b;

return *this;
}


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I ripped this from a friend:

void MatrixInverse(float* a_Output, float* a_OpenGLMatrix)
{
float tcell[16];

float tx = -a_OpenGLMatrix[12];
float ty = -a_OpenGLMatrix[13];
float tz = -a_OpenGLMatrix[14];

for (int h = 0; h < 3; h++)
{
for (int v = 0; v < 3; v++)
{
tcell[h + v * 4] = a_OpenGLMatrix[v + h * 4];
}
}

for (int i = 0; i < 11; i++)
{
a_Output[i] = tcell[i];
}

a_Output[12] = tx * a_OpenGLMatrix[0] + ty * a_OpenGLMatrix[4] + tz * a_OpenGLMatrix[8];
a_Output[13] = tx * a_OpenGLMatrix[1] + ty * a_OpenGLMatrix[5] + tz * a_OpenGLMatrix[9];
a_Output[14] = tx * a_OpenGLMatrix[2] + ty * a_OpenGLMatrix[6] + tz * a_OpenGLMatrix[10];
}


When I multiply the new matrix with the old matrix I get the identity matrix, which is supposed to be a check to see if the function is working.

However, now I can't find my shadow square anymore. I'm going to try a bunch of scenes.

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If the camera is effecting the shadows it's either that the light matricies change when the camera changes, or the inverse matrix isn't un-doing the effects of the camera in the shader.

Is your shadowmap capturing the whole scene? Maybe put the shadowmap texture on a quad and post a picture.

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