Mali GPU User Interface Engine Application Development Guide

Tutorial on Constructing Custom Shaders6.3.3 Locations and view transformations as vectors and matricesUse the setUniform() and setUniformMatrix() functions to pass a vector or matrix to the shaderprogram.The code in Example 6-8 passes vectors representing the light and camera position:Example 6-8 Passing a vector uniform to the shaderfloat angleRad = 23.0f/(180*3.15149265);vec3 camPos=vec3(75.0f * cos(angleRad), 75.0f * sin(angleRad), 0.0f);vec3 lightPosition(75.0f, 75.0f, 0.0f);context->setUniform("LIGHT_POSITION", lightPosition);context->setUniform("CAMERA_POSITION", camPos);glClearColor(0.0f, 0.0f, 0.0f, 1.0f);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);glEnable(GL_CULL_FACE);glCullFace(GL_BACK);glEnable(GL_DEPTH_TEST);// calculate the camera positionvec3 camPos(60.0f, 0.0f, 0.0f);context->setUniform("CAM_POS", camPos);// the world is formed from time-based rotationsmat4 world = mat4::rotation(t*10.0f, vec3(1,1,0))*mat4::rotation(t, vec3(1,0,1));// the view is constructed from the camera location and viewing orientationsmat4 view = mat4::lookAt( camPos, vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 0.0f, 1.0f) );// the perspective transform is specified by field-of-view, aspect ratio,// near plane, and far planemat4 proj = mat4::perspective(270.0f, 4.0f/3.0f, 1.0f, 500.0f);// combine the calculated matrices to a world-view-projection matrixwvpMatrix = proj * view * world;// set the uniform values to pass to the shaderscontext->setUniformMatrix("WORLD_VIEW_PROJECTION", wvpMatrix);context->setUniformMatrix("WORLD", world.toMat3());The vertex shader reads the vertex values and calculates the lighting as shown in Example 6-9:Example 6-9 Using a matrix uniform in the vertex shaderuniform mat4 WORLD_VIEW_PROJECTION;uniform mat3 WORLD;uniform vec3 LIGHT_POSITION;uniform vec3 CAMERA_POSITION;attribute vec4 POSITION;attribute vec3 NORMAL;varying vec3 vNormal;varying vec3 vLightVector;varying vec3 vCameraVector;void main(void){gl_Position = WORLD_VIEW_PROJECTION * POSITION;ARM DUI 0527A-02a Copyright © 2010 ARM. All rights reserved. 6-10ID070710Non-Confidential - Draft - Beta