Hello,
I am working on a terrain generator using heightmaps for a class I am currently in and I seem to have come across a problem which I cannot figure out, as I have very little experience using openGL.
I have calculated a shadowmap based on my heightmap and saved it to my terrain file as simply a raw 8 bit image. However, when I attempt to load it into my graphics card I believe it thinks I am loading in a 24 bit image.
I'm not sure so I will not speculate further, I'll just show you what is going on.
When the shadow map is applied it looks like this:
However, if I output the shadowmap as a .BMP it looks like it should,
This is my shader source:
Vertex Shader:
void main()
{
gl_Position = gl_ProjectionMatrix*gl_ModelViewMatrix*gl_Vertex;
gl_TexCoord[0] = gl_MultiTexCoord0;
}
Fragment shader:
uniform sampler2D sand;
uniform sampler2D grass;
uniform sampler2D rock;
uniform sampler2D snow;
uniform sampler2D shadowmap;
uniform sampler2D alphamap;
void main(void)
{
vec4 shadow = texture2D( shadowmap, gl_TexCoord[0].xy ).rgba;
vec4 alpha = texture2D( alphamap, gl_TexCoord[0].xy ).rgba;
vec4 tex0 = texture2D( sand, gl_TexCoord[0].xy * 8.0 );
vec4 tex1 = texture2D( grass, gl_TexCoord[0].xy * 8.0 );
vec4 tex2 = texture2D( rock, gl_TexCoord[0].xy * 8.0 );
vec4 tex3 = texture2D( snow, gl_TexCoord[0].xy * 8.0 );
tex0 *= alpha.r; // Red channel - sand/below sealevel
tex1 = mix( tex0, tex1, alpha.g ); // Green channel - grass/above sealevel
tex2 = mix( tex1, tex2, alpha.b ); // Blue channel - rock/steep slopes
vec4 outColor = mix( tex2, tex3, alpha.a ); // Alpha channel - snow/high altitude
outColor *= shadow;
gl_FragColor = clamp( outColor, 0.0, 1.0 );
}
and this is how I load in the image:
GLuint texture_id;
glGenTextures(1, &texture_id);
glBindTexture(GL_TEXTURE_2D, texture_id);
/* set texture parameters */
if(GL_EXT_texture_filter_anisotropic)
{
float MaxAnisotropic;
glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &MaxAnisotropic);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, MaxAnisotropic);
}
// set parameters
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
// create mipmaps
gluBuild2DMipmaps( GL_TEXTURE_2D, internal_format, width, height, format, type, data );
This is how I call it:
GraphicsManager::GetSingleton().LoadRawTexture("shadowmap", 1, map->get_width(), map->get_height(), GL_LUMINANCE, GL_UNSIGNED_BYTE, map->get_shadowmap());
I use a hashmap in my graphics manager and hash the names of textures, that is why I have "shadowmap" as the 1st argument. That may be a bad way of doing it, I don't know, but I know that it works for what I am currently doing. So that isn't the issue here.
All I do when I render is
// set uniform for shadowmap
sampler_loc = glGetUniformLocationARB(terrain_shader, "shadowmap");
glActiveTextureARB(GL_TEXTURE4);
GraphicsManager::GetSingleton().SetTexture("shadowmap");
glUniform1iARB(sampler_loc, 4);
If it comes down to it I will store the image as RGB, just repeating the 8bit value, but as heightmaps can get large, that seems far from a good solution.
[Edited by - melbow on May 1, 2009 10:14:46 AM]
