Hi,
I face the problem that the pure compilation of a shader breaks other shaders.
The relevant part of my scene graph looks as follows:
Code:
* root (osg::Group)
* SkyGeode (osg::Geode)
*Sky (subclass of osg::Geometry)
* OtherGroup (subclass of osg::Group)
The Sky geometry object compiles its own shader and sets its uniforms once on
creation. This alone works very well.
As soon as I compile a vertex shader in the constructor of OtherGroup, the sky
rendering fails (i.e. the calculated color is not reasonable anymore). I have
found out that this is caused by some uniforms not being set correctly.
However, I haven't changed anything about them. They should still have their
values from the beginning.
Here is the second vertex shader (compiled from OtherGroup):
Code:
#version 150
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect instanceData;
uniform mat4 osg_ModelViewProjectionMatrix;
in vec4 vertex;
in vec3 normal;
out vec4 vertexColor;
const vec3 directionToLight = normalize(vec3(1, -2, 3));
void main(void)
{
vec2 instanceCoord = vec2(gl_InstanceID % 256, gl_InstanceID / 256);
vec4 pos = texture2DRect(instanceData, instanceCoord);
pos.w = 0;
gl_Position = osg_ModelViewProjectionMatrix * (vec4(vertex, 1) + pos);
float diffuse = max(0, dot(normal, directionToLight));
float ambient = 0.2;
float color = diffuse + ambient;
vertexColor = vec4(color, color, color, 1);
}
This problem occurs even though OtherGroup does not have any drawable children.
The vertex shader is not even added to a program. It is just compiled. I
compile it as follows (in the constructor of OtherGroup):
Code:
osg::ref_ptr<osg::Shader> vs = osgDB::readShaderFile(osg::Shader::VERTEX,
"glsl/shader.vert");
For debugging purposes, I have output some uniforms as the color in the sky
fragment shader. As long as the compilation of the second vertex shader is not
present, this gives me a reddish color. Once I insert this single line, the sky
turns yellow. That's how I confirmed that the uniforms must be wrong.
I have enabled useModelViewAndProjectionUniforms for the camera, but not
useVertexAttributeAliasing.
I really can't understand why the sole compilation of a shader causes other
parts of the application to fail. Am I missing something here? It appears that
if the shader contains syntax errors (of which I am not notified btw), the sky
renders just fine.
I have also found out that this problem only occurs if the shader is loaded
through osgDB::readShaderFile(). If I load it directly as follows, everything
is working again. However, the GLSL plugin basically does the same (plus some
osgDB caching):
Code:
osgDB::ifstream fin(osgDB::findDataFile("glsl/shader.vert").c_str(),
std::ios::in | std::ios::binary);
std::stringstream ss;
ss << fin.rdbuf();
osg::ref_ptr<osg::Shader> vs = new osg::Shader(osg::Shader::VERTEX, ss.str());
Nico
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=61525#61525
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