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| public:t-vien-07-1:lab_9_materials [2007/03/09 04:17] – hannes | public:t-vien-07-1:lab_9_materials [2024/04/29 13:33] (current) – external edit 127.0.0.1 |
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| * Download and unzip the [[http://www.ru.is/kennarar/hannes/classes/ve2007/Lab9Assets.zip|Lab 9 Asset File]] into your working directory | * Download and unzip the [[http://www.ru.is/kennarar/hannes/classes/ve2007/Lab9Assets.zip|Lab 9 Asset File]] into your working directory |
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| - **Diffuse and Specular Lighting (per pixel):**\\ In your **shadertest2.py**, load **shader3.sha** instead of **shader2.sha**. This shader has moved the calculation of the diffuse color attenuation into the fragment shader by passing the Light Vector and the Normal Vector over there from the vertex shader. Finish adding the specular attenuation value to the light calculation in this shader using the fragment shader to calculate a per-pixel Light Reflection Vector. Once you get this working, notice the drastic difference in quality between the per-vertex specular lighting and the per-pixel specular lighting. | - **Diffuse and Specular Lighting (per pixel):**\\ In your **shadertest2.py**, load **shader3.sha** instead of **shader2.sha**. This shader has moved the calculation of the diffuse color attenuation into the fragment shader by passing the Light Vector and the Normal Vector over there from the vertex shader. Finish adding the specular attenuation value to the light calculation in this shader using the fragment shader to calculate a per-pixel Light Reflection Vector. Once you get this working, notice the drastic difference in quality between the per-vertex specular lighting and the per-pixel specular lighting. |
| - **Texture:**\\ Let's add a texture to your sphere. Add the following lines to your python code (after you load the sphere model): <code python> | - **Texture:**\\ Let's add a texture to your sphere. Add the following lines to your python code (after you load the sphere model): <code python> |
| diffuse_map = loader.loadTexture("./Models/Textures/bricks.tga") | diffuse_map = loader.loadTexture("./Models/Textures/bricks.png") |
| ts0 = TextureStage( 'level0' ) | ts0 = TextureStage( 'level0' ) |
| sphere.setTexture(ts0, diffuse_map) | sphere.setTexture(ts0, diffuse_map) |
| mat_tangent[2] = vtx_normal; | mat_tangent[2] = vtx_normal; |
| </code> Once this new transformation matrix has been created inside the vertex shader, both the View Vector and the Light Vector should be projected into tangent space through a simple multiplication with this matrix. Once these vectors arrive inside the fragment shader, they should already be in tangent space and the third important component in our lighting calculations, namely the normal, should now be looked up in the normal map accessed through **tex_0_n** (note however that the texture stores components in the 0-1 range but we want them in the -1-1 range, so you need to correct the value when you look it up like this **tex2D(normalmap, texturecoordinate)*2-1**). Since the normal that we're reading from the normal map is already in tangent space (that's how they're stored in normal maps - and that explains why we needed to transform the other vectors), we can now proceed with the lighting calculations, just like we did in model space. See if you can make this work. | </code> Once this new transformation matrix has been created inside the vertex shader, both the View Vector and the Light Vector should be projected into tangent space through a simple multiplication with this matrix. Once these vectors arrive inside the fragment shader, they should already be in tangent space and the third important component in our lighting calculations, namely the normal, should now be looked up in the normal map accessed through **tex_0_n** (note however that the texture stores components in the 0-1 range but we want them in the -1-1 range, so you need to correct the value when you look it up like this **tex2D(normalmap, texturecoordinate)*2-1**). Since the normal that we're reading from the normal map is already in tangent space (that's how they're stored in normal maps - and that explains why we needed to transform the other vectors), we can now proceed with the lighting calculations, just like we did in model space. See if you can make this work. |
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