The Orange book, section 16.2, lists implementing diffuse lighting as: void main() { vec3 N = normalize(gl_NormalMatrix * gl_Normal); vec4 V = gl_ModelViewMatrix * gl_vertex; vec3 L = normalize(lightPos - V.xyz); gl_FrontColor = gl_Color * vec4(max(0.0, dot(N, L)); } However, when I run this, the lighting changes when I move m...
uniform sampler2D sampler0; uniform vec2 tc_offset[9]; void blur() { vec4 sample[9]; for(int i = 0; i < 9; ++i) sample[i] = texture2D(sampler0, gl_TexCoord[0].st + tc_offset[i]); gl_FragColor = (sample[0] + (2.0 * sample[1]) + sample[2] + (2.0 * sample[3]) + sample[4] + 2.0 * sample[5] + sample[6] + 2.0 * sample[7]...
Hello stack overflow. I am trying to add some post-processing capabilities to a program. The rendering is done using openGL. I just want to allow the program to load some home made fragment shader and use them on the video stream. I wrote a little piece of shader using "OpenGL Shader Builder" that just turns a texture in grayscale. The...
I'm trying to use the unscaled (true distance from the front clipping plane) distance to objects in my scene in a GLSL fragment shader. The gl_FragCoord.z value is smaller than I expect. In my vertex shader, I just use ftransform() to set gl_Position. I'm seeing values between 2 and 3 when I expect them to be between 15 and 20. How c...
I'm trying to implement an algorithm from a graphics paper and part of the algorithm is rendering spheres of known radius to a buffer. They say that they render the spheres by computing the location and size in a vertex shader and then doing appropriate shading in a fragment shader. Any guesses as to how they actually did this? The po...
I'm trying to wrap my head around shaders in GLSL, and I've found some useful resources and tutorials, but I keep running into a wall for something that ought to be fundamental and trivial: how does my fragment shader retrieve the color of the current fragment? You set the final color by saying gl_FragColor = whatever, but apparently th...
When I set glStencilFunc( GL_NEVER, . . . ) effectively disabling all drawing, and then run my [shader-bound] program I get no performance increase over letting the fragment shader run. I thought the stencil test happened before the fragment program. Is that not the case, or at least not guaranteed? Replacing the fragment shader with one...
I was following this tutorial using Apple's OpenGL Shader Builder (tool similar to Nvidia's fx composer, but simpler). I could easily apply the filters, but I don't understand if they worked correct (and if so how can I improve the output). For example the blur filter: OpenGL itself does some image processing on the textures, so if they...
Hi all, I'm playing about with some vertex and fragment shaders using Cg on my little netbook (running Linux). Clearly I'm going to frequently hit resource limits for my graphics controller, so was wondering if there's a nice way to run the shaders on the CPU, just to test them. Something like D3D's refrast... TIA Andy ...
I'll try to keep this simple. I want a way to access the normal information of the scene, from the Frame Buffer output (or similar). The same way one is able to access the Depth Buffer using glGetTexImage and GL_DEPTH_COMPONENT. I know I could set up a fragment shader which outputs the normal information in RGB color space, which could...
I'm trying to blur a depth texture by blurring & blending mipmap levels in a fragment shader. I have two frambuffer objects: 1) A color frambuffer with a depth renderobject attached. 2) A z framebuffer with a depth texture attached. Once I render the scene to the color framebuffer object, I then blit to the depth buffer object, and ca...
I'm having issues trying to get a texture loaded into VRAM. I'm using OpenGL on Mac OS X. I have geometry that I've successfully renderer by passing a color into my fragment shader. However, as soon as I try to load a texture, no geometry gets rendered and I can only see the background color. Here's my texture loading code: char ima...