Glsl dynamic reflection using FBO

OpenGL
1

hi.
Application has skybox using cube mapping, floor and 2 simple cube. i want to apply dynamic reflection mapping on one of the cube. but reflected cube looks weirdly.how can i fix problem. where i made wrong. code is below. thanks in advence

//////in init()


	glGenTextures(1, &box2CubeMap);
	glBindTexture(GL_TEXTURE_CUBE_MAP, box2CubeMap);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
	for(int i=0; i<6; ++i)
	{
		glTexImage2D(cube[i], 0, GL_RGB, 512, 512, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
	}


		// FBO and RenderObject
	glGenRenderbuffers(1, &box2depthRender);
	glBindRenderbuffer(GL_RENDERBUFFER, box2depthRender);
	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, 512, 512);
	glBindRenderbuffer(GL_RENDERBUFFER, 0);
	glGenFramebuffers(1, &fbo);
	glBindFramebuffer(GL_FRAMEBUFFER, fbo);	
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthTexture, 0);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, box2CubeMap, 0);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, box2CubeMap, 0);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, box2CubeMap, 0);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, box2CubeMap, 0);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, box2CubeMap, 0);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, box2CubeMap, 0);
		
		GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
		if(status != GL_FRAMEBUFFER_COMPLETE)
		{
			exit(0);
		}
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

/////in draw function


	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, 0, 0);
	glBindRenderbuffer(GL_RENDERBUFFER, box2depthRender);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, box2depthRender);
        // generete cube mapping
	generateENV(Vector3D(5, 3, 0));
	glBindRenderbuffer(GL_RENDERBUFFER, 0);
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
box2prg->use();
glUniformMatrix4fv(invViewMat, 1, GL_FALSE, invView.m);
	glPushMatrix();
		glTranslatef(5,3,0);
	glActiveTexture(GL_TEXTURE6);
	glBindTexture(GL_TEXTURE_CUBE_MAP, box2CubeMap);
	glEnable(GL_MULTISAMPLE);
		box2();
	glPopMatrix();
box2prg->disable();

///// generateENV function


void generateENV(const Vector3D& v)
{
	glMatrixMode(GL_PROJECTION);
		glPushMatrix();
		glLoadIdentity();
		gluPerspective(90, 1, 0.5, 500);
	glMatrixMode(GL_MODELVIEW);
		glPushMatrix();
		
	for(GLenum i= GL_TEXTURE_CUBE_MAP_POSITIVE_X ; 
		i < GL_TEXTURE_CUBE_MAP_POSITIVE_X +6; ++i)
	{
		glLoadIdentity();
		switch(i)
		{
		case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
			{
				gluLookAt(v.v[0], v.v[1], v.v[2], 1, 0, 0, 0, -1, 0);				
				break;
			}
		case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
			{
				gluLookAt(v.v[0], v.v[1], v.v[2], -1, 0, 0, 0, -1, 0);				
				break;
			}
		case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
			{
				gluLookAt(v.v[0], v.v[1], v.v[2], 0, 1, 0, 0, 0, 1);				
				break;
			}
		case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
			{
				gluLookAt(v.v[0], v.v[1], v.v[2], 0, -1, 0, 0, 0, -1);				
				break;
			}
		case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
			{
				gluLookAt(v.v[0], v.v[1], v.v[2], 0, 0, 1, 0, -1, 0);				
				break;
			}
		case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
			{
				gluLookAt(v.v[0], v.v[1], v.v[2], 0, 0, -1, 0, -1, 0);				
				break;
			}
	
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, i, box2CubeMap, 0);

		glPushMatrix();
		glActiveTexture(GL_TEXTURE0);
		glEnable(GL_TEXTURE_CUBE_MAP);
		glBindTexture(GL_TEXTURE_CUBE_MAP, skyTexture);
		glLoadIdentity();
		GLfloat m[16];
		glGetFloatv(GL_MODELVIEW_MATRIX, m);
		m[12] = 0; m[13] = 0; m[14] = 0;
		glMultMatrixf(m);
		sky();
		glDisable(GL_TEXTURE_CUBE_MAP);	
		glPopMatrix();

		
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, diffuseMapTexture);
	glEnable(GL_TEXTURE_2D);
//prg->use();
	glPushMatrix();
		floor();
	glPopMatrix();	
//prg->disable();
	glDisable(GL_TEXTURE_2D);

//box1prg->use();
	glPushMatrix();
		glTranslatef(-3,2,0);
		box1();
	glPopMatrix();
//box1prg->disable();
	
	glGenerateMipmap(GL_TEXTURE_CUBE_MAP);
		}
	}

		glMatrixMode(GL_PROJECTION);
		glPopMatrix();
		glMatrixMode(GL_MODELVIEW);
		glPopMatrix();
}

vertex shader


varying vec4 shadowCoord;
varying vec3 R;

uniform mat4 invView;

void main()
{
	gl_Position = ftransform();
	vec4 pos = gl_ModelViewMatrix * gl_Vertex;
	vec3 E = pos.xyz;
	vec3 N = gl_NormalMatrix * gl_Normal;
	E = normalize(E);
	N = normalize(N);
	R = reflect(E, N);
	R = (invView * vec4(R, 0.0)).xyz;
	shadowCoord = gl_TextureMatrix[5] * pos;
}

fragment shader


varying vec4 shadowCoord;
varying vec3 R;

uniform sampler2D depthTexture;
uniform samplerCube cubeTexture;

void main()
{
	float shadowFactor = texture2DProj(depthTexture, shadowCoord).g;
	vec4 color = textureCube(cubeTexture, R.xyz);
	gl_FragColor = color ;//* shadowFactor;
}

scene photo

2

Did you set the correct texture unit for the cubemap which is 6? I don’t see you setting it for the shader but only the function that seems to be your draw call box2().

box2prg->use();
glUniformMatrix4fv(invViewMat, 1, GL_FALSE, invView.m);
glPushMatrix();
glTranslatef(5,3,0);
glActiveTexture(GL_TEXTURE6);
glBindTexture(GL_TEXTURE_CUBE_MAP, box2CubeMap);
glEnable(GL_MULTISAMPLE);
box2();
glPopMatrix();
box2prg->disable();

I don’t see a glUniform1i(“cubeTexture”, 6);

3

thanks ravage for your reply. yes i set texture unit

/// in init()


	box2prg->use();
			box2loc5Depth    = glGetUniformLocation(box2prg->program, "depthTexture");
			box2loc6Cube	 = glGetUniformLocation(box2prg->program, "cubeTexture");
			invViewMat       = glGetUniformLocation(box2prg->program, "invView");	
			glUniform1i(box2loc5Depth, 5);
			glUniform1i(box2loc6Cube, 6);

	box2prg->disable();

i changed vertex shader code to see wheter cube mapping is rendered correctly. Changed code and screen output is below

// vertex shader


// R = (invView * vec4(R, 0.0)).xyz;
R = normalize(gl_NormalMatrix * gl_Normal);

but i have still problem. i think my problem arise from render to cube texture. but i cant find my mistake.

4

Use the normal instead of the reflect® vector just to see if you at least get back the environment. If this doesn’t give you back the environment then the setup for the fbo is weird.

vec4 color = textureCube(cubeTexture, normal.xyz);

I also had a suggestion if this by itself doesn’t show any results.

you have:
gluLookAt(v.v[0], v.v[1], v.v[2], 1, 0, 0, 0, -1, 0);
etc.

Change it to:
gluLookAt(v.v[0], v.v[1], v.v[2], v.v[0]+1, v.v[1], v.v[2], 0, -1, 0);
etc.

Doing it the way you have it would cause problems if you are not at the position (0,0,0).

5

problem was solved. i have forgotten put curly bracket end of switch statement. thanks ravage for your help. good day

6

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