1 | /* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */ |
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2 | /* |
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3 | * ---------------------------------------------------------------------- |
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4 | * Render to vertex array |
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5 | * |
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6 | * This class implements "render to vertex array" functionality |
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7 | * using vertex and pixel buffer objects (VBO and PBO). |
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8 | * |
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9 | * Operation: |
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10 | * 1. A buffer object is created |
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11 | * 2. The buffer object is bound to the pixel pack (destination) buffer |
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12 | * 3. glReadPixels is used to read from the frame buffer to the buffer object |
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13 | * 4. The buffer object is bound to the vertex array |
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14 | * 5. Vertex array pointers are set |
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15 | * |
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16 | * Usage: |
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17 | * 1. Create a floating point pbuffer |
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18 | * 2. Create a RenderVertexArray object for each vertex attribute |
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19 | * you want to render to |
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20 | * 3. Render vertex data to pbuffer using a fragment program (could |
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21 | * use multiple draw buffers here) |
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22 | * 4. Call Read() method to read data from pbuffer to vertex array |
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23 | * 5. Call SetPointer() method to set vertex array pointers |
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24 | * 6. Set any other other static vertex array attribute pointers |
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25 | * 7. Render geometry as usual using glDrawArrays or glDrawElements |
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26 | * |
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27 | * ====================================================================== |
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28 | * AUTHOR: Wei Qiao <qiaow@purdue.edu> |
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29 | * Purdue Rendering and Perceptualization Lab (PURPL) |
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30 | * |
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31 | * Copyright (c) 2004-2013 HUBzero Foundation, LLC |
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32 | * |
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33 | * See the file "license.terms" for information on usage and |
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34 | * redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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35 | * ====================================================================== |
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36 | */ |
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37 | #include <stdio.h> |
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38 | |
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39 | #include <GL/glew.h> |
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40 | #include <GL/gl.h> |
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41 | |
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42 | #include "RenderVertexArray.h" |
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43 | #include "Trace.h" |
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44 | |
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45 | using namespace nv; |
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46 | |
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47 | RenderVertexArray::RenderVertexArray(int nverts, GLint size, GLenum type) : |
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48 | _usage(GL_STREAM_COPY_ARB), |
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49 | _nverts(nverts), |
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50 | _size(size), |
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51 | _type(type) |
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52 | { |
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53 | switch (_type) { |
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54 | case GL_HALF_FLOAT_NV: |
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55 | _bytesPerComponent = 2; |
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56 | break; |
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57 | case GL_FLOAT: |
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58 | _bytesPerComponent = sizeof(float); |
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59 | break; |
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60 | default: |
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61 | ERROR("unsupported RenderVertexArray type"); |
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62 | return; |
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63 | } |
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64 | |
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65 | // create the buffer object |
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66 | glGenBuffersARB(1, &_buffer); |
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67 | glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, _buffer); |
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68 | glBufferDataARB(GL_PIXEL_PACK_BUFFER_ARB, |
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69 | _nverts*_size*_bytesPerComponent, |
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70 | 0, _usage); // undefined data |
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71 | glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, 0); |
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72 | |
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73 | // set equivalent image format |
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74 | switch(_size) { |
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75 | case 1: |
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76 | _format = GL_LUMINANCE; |
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77 | break; |
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78 | case 3: |
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79 | _format = GL_RGB; |
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80 | break; |
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81 | case 4: |
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82 | _format = GL_RGBA; |
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83 | break; |
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84 | default: |
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85 | ERROR("unsupported RenderVertexArray size"); |
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86 | return; |
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87 | } |
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88 | } |
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89 | |
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90 | RenderVertexArray::~RenderVertexArray() |
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91 | { |
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92 | glDeleteBuffersARB(1, &_buffer); |
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93 | } |
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94 | |
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95 | void |
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96 | RenderVertexArray::loadData(void *data) |
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97 | { |
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98 | // load data to buffer object |
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99 | glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, _buffer); |
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100 | glBufferDataARB(GL_PIXEL_PACK_BUFFER_ARB, |
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101 | _nverts*_size*_bytesPerComponent, |
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102 | data, _usage); |
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103 | glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, 0); |
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104 | } |
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105 | |
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106 | void |
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107 | RenderVertexArray::read(int w, int h) |
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108 | { |
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109 | // bind buffer object to pixel pack buffer |
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110 | glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, _buffer); |
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111 | |
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112 | // read from frame buffer to buffer object |
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113 | glReadPixels(0, 0, w, h, _format, _type, 0); |
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114 | |
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115 | glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, 0); |
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116 | } |
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117 | |
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118 | void |
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119 | RenderVertexArray::setPointer(GLuint index) |
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120 | { |
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121 | // bind buffer object to vertex array |
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122 | glBindBufferARB(GL_ARRAY_BUFFER_ARB, _buffer); |
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123 | //glVertexAttribPointerARB(index, _size, _type, GL_FALSE, 0, 0); //doesn't work |
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124 | glVertexPointer(_size, _type, 0, 0); |
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125 | |
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126 | glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0); |
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127 | } |
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