Mali GPU User Interface Engine Application Development Guide

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Tutorial on Constructing Custom ShadersThe fragment shader outputs gl_FragColor which is the global color value for the fragment. Theshader might just assign a fixed color value to all fragments in the shape but it can also:• read uniform values passed to the fragment shader by the application• use a texture bitmap to locate the bitmap pixel to use as the color for the fragment• use the varying output values from the vertex shader to modify the fragment color• use local variables or functions to simplify complex calculations• use matrix transformations to calculate lighting effects to apply• use a stencil to return fragment color for points that fit the specified condition.Figure 6-2 shows the data paths between the application, shader programs, and global context:Vertex shader codeAttributesPOSITIONCOLOR...UniformsWORLD_VIEW_PROJECTIONCAMERA_POSITIONWORLDModelViewMatrix...Global variablesgl_Positiongl_Pointsizegl_PointCoordgl_FrontFacinggl_FragColor...UniformsDIFFUSE_LIGHTSPECULAR_LIGHTAMBIENTDIFFUSE_CONTRIBUTIONSPECULAR_CONTRIBUTION...gl_Positiongl_FragColorVertexshaderLocal variablesvTexCoordvLightVectorvCameraVectorVaryingsvTexCoordvLightVectorvCameraVectorvColorvViewVectorFragmentshaderLocal variablesnormalviewVectorreflectionVectorFragment shader codeTexture sampler(typically from a bitmap file)Figure 6-2 Simplified view of shader data flowThe fragment shader might also use matrix transformations to calculate the fragment colorbased on all of the lighting sources.To draw a geometric object, for example a chair:1. All vertices associated with the chair must be known. For 3D graphics, the vertices arerepresented by x, y, and z coordinates. (If not explicitly specified, the value of w isassumed to be 1 for points in 3D space.)2. The vertices must be grouped into geometric primitives.ARM DUI 0527A-02a Copyright © 2010 ARM. All rights reserved. 6-3ID070710Non-Confidential - Draft - Beta
Tutorial on Constructing Custom Shaders3. The order to draw the primitives must be determined. Breaking down a complex shapeinto a sequence of primitive shapes is called modeling.The chair is now modeled in its own 3D coordinate system. The next steps position thatchair in a larger environment and determine how it looks from the camera.4. Specify where the camera is located in 3D space, where the camera is pointing, where isthe top of the camera, and the viewing angle for the camera.5. A viewing transform calculates where the viewing frustum is in world coordinates.6. A projection transform maps the vertex to the display space (clip coordinates).7. Modify the result to produce the perspective effects.8. The vertex shader uses the interpolated position on the primitive to map the transformedand clipped coordinates to the display window.9. The fragment shader converts fragments to colored pixels in the frame buffer.ARM DUI 0527A-02a Copyright © 2010 ARM. All rights reserved. 6-4ID070710Non-Confidential - Draft - Beta
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MaliGPU User Interface EngineVersio
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ContentsMali GPU User Interface Eng
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List of TablesMali GPU User Interfa
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List of FiguresFigure 4-17 Environm
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PrefaceAbout this bookThis is the M
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PrefaceFeedbackARM welcomes feedbac
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Introduction1.1 About the Mali GPU
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IntroductionProxygetLoader()LoaderA
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Chapter 2Tutorial on the System Cla
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Tutorial on the System Classes2.2 C
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Tutorial on the System ClassesFigur
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Tutorial on the System ClassesDrawi
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Chapter 3Tutorial on Drawing 2D Sha
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Tutorial on Drawing 2D Shapes...con
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Tutorial on Drawing 2D ShapesFor ea
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Tutorial on Drawing 2D ShapesFigure
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Tutorial on Drawing 3D Shapes4.1 Dr
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