I want make a skybox in GLSL, but I have a problem. Before this I render a cube and one texture for all cube and it’s working. I make a 6 bmp files for skybox and do it in code:
First, I make a handle for skybox buffer, 72 element array and 6 handles for textures:
GLuint skyID;
GLuint sky1;
GLuint sky2;
GLuint sky3;
GLuint sky4;
GLuint sky5;
GLuint sky6;
GLfloat * SkyBox = new GLfloat[72];
Then, in main function I initialized this array for skybox coordinates. Later, I create 2 functions for loading shaders (one shader to normal texturing and one for skybox):
SetShaders("myShader.vert.txt","myShader.frag.txt");
CreateProgram();
SetShadersSky("skybox.vert.txt","skybox.frag.txt");
CreateProgramSky();
Next, I create buffer for skybox coord and load textures:
loadBitmapFromFile("skybox1.bmp",&bitmap);
glGenTextures(1,&sky1);
glBindTexture(GL_TEXTURE_2D,sky1);
gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, bitmap.width, bitmap.height, GL_RGB, GL_UNSIGNED_BYTE, bitmap.data);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);
I do this 6 times, for 6 textures.
Now is the time for a render function:
void RenderScene()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glClearColor(0.0,0.0,0.0,1.0);
glEnable(GL_DEPTH_TEST);
glUseProgram(SkyBoxP);
glBindBuffer(GL_ARRAY_BUFFER,skyID);
glBufferData(GL_ARRAY_BUFFER,sizeof(float)*72,SkyBox,GL_DYNAMIC_DRAW);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3,GL_FLOAT,0,0);
glEnableVertexAttribArray(glGetAttribLocation(Program,"sky_in"));
glBindBuffer(GL_ARRAY_BUFFER,texID);
glBufferData(GL_ARRAY_BUFFER,sizeof(float)*48,Tex,GL_DYNAMIC_DRAW);
glVertexAttribPointer(glGetAttribLocation(SkyBoxP,"sky_in"),2,GL_FLOAT,GL_FALSE,0,0);
glDrawArrays(GL_QUADS,0,72);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,sky1);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);
textureLocation = glGetUniformLocation(Program,"sky1");
glUniform1i(textureLocation,0);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D,sky2);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);
textureLocation = glGetUniformLocation(Program,"sky2");
glUniform1i(textureLocation,1);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D,sky3);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);
textureLocation = glGetUniformLocation(Program,"sky3");
glUniform1i(textureLocation,2);
glActiveTexture(GL_TEXTURE3);
glBindTexture(GL_TEXTURE_2D,sky4);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);
textureLocation = glGetUniformLocation(Program,"sky4");
glUniform1i(textureLocation,3);
glActiveTexture(GL_TEXTURE4);
glBindTexture(GL_TEXTURE_2D,sky5);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);
textureLocation = glGetUniformLocation(Program,"sky5");
glUniform1i(textureLocation,4);
glActiveTexture(GL_TEXTURE5);
glBindTexture(GL_TEXTURE_2D,sky6);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);
textureLocation = glGetUniformLocation(Program,"sky6");
glUniform1i(textureLocation,5);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glUseProgram(0);
glBindTexture(GL_TEXTURE_2D,0);
glUseProgram(Program);
glBindBuffer(GL_ARRAY_BUFFER,boxID);
glBufferData(GL_ARRAY_BUFFER,sizeof(float)*72,Box,GL_DYNAMIC_DRAW);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3,GL_FLOAT,0,0);
glEnableVertexAttribArray(glGetAttribLocation(Program,"tex_in"));
glBindBuffer(GL_ARRAY_BUFFER,texID);
glBufferData(GL_ARRAY_BUFFER,sizeof(float)*48,Tex,GL_DYNAMIC_DRAW);
glVertexAttribPointer(glGetAttribLocation(Program,"tex_in"),2,GL_FLOAT,GL_FALSE,0,0);
glDrawArrays(GL_QUADS,0,72);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,texture);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);
textureLocation = glGetUniformLocation(Program,"texture");
glUniform1i(textureLocation,0);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glUseProgram(0);
glBindTexture(GL_TEXTURE_2D,0);
}
And shaders:
Vertex:
attribute vec2 sky_in;
varying vec2 sky;
void main()
{
glTexCoord[0] = vec4(sky_in,0.0,0.0);
sky = gl_TexCoord[0];
glTexCoord[1] = vec4(sky_in,0.0,0.0);
sky = gl_TexCoord[1];
glTexCoord[2] = vec4(sky_in,0.0,0.0);
sky = gl_TexCoord[2];
glTexCoord[3] = vec4(sky_in,0.0,0.0);
sky = gl_TexCoord[3];
glTexCoord[4] = vec4(sky_in,0.0,0.0);
sky = gl_TexCoord[4];
glTexCoord[5] = vec4(sky_in,0.0,0.0);
sky = gl_TexCoord[5];
gl_Position = ftransform();
}
Fragment:
uniform sampler2D sky1;
uniform sampler2D sky2;
uniform sampler2D sky3;
uniform sampler2D sky4;
uniform sampler2D sky5;
uniform sampler2D sky6;
varying vec2 sky;
void main()
{
vec4 texel0, texel1, texel2, texel3, texel4, texel5, color;
texel0 = texture2D(sky1,sky);
texel1 = texture2D(sky2,sky);
texel2 = texture2D(sky3,sky);
texel3 = texture2D(sky4,sky);
texel4 = texture2D(sky5,sky);
texel5 = texture2D(sky6,sky);
color = mix(texel0,texel1,texel2,texel3,texel4,texel5);
gl_FragColor = color;
}
Only, what I see is textured cube (but textured in one texture) in white box (this is skybox, but not textured). My problem is that, skybox isn’t textured and cube isn’t textured in few textures, but in one.
I hope that, you can forgive me about my poor English.
Take a step back and rethink this.