Developer Documentation

AntiAliasing.hh
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40 \*===========================================================================*/
41
42 //=============================================================================
43 //
44 // Helper classes for Anti-Aliasing of render targets
45 //
46 //=============================================================================
47
48
49 #ifndef ANTI_ALIASING_HH
50 #define ANTI_ALIASING_HH
51
52
53 //== INCLUDES =================================================================
54
55 // GL
56 #include <ACG/GL/acg_glew.hh>
57 #include <ACG/GL/globjects.hh>
58 #include <ACG/GL/gl.hh>
59
60 // C++
61 #include <vector>
62
63
64 //== FORWARD DECLARATIONS =====================================================
65
66 namespace GLSL{
67 class Program;
68 }
69
70
71 //== NAMESPACES ===============================================================
72
73 namespace ACG {
74
75
76 //== CLASS DEFINITION =========================================================
77
78
79 /*
80 OpenGL MSAA:
81
82 A post-processing fragment shader has to compute colors per sample rather than per pixel for full MSAA.
83 Sample values are then weighted by filter weights to obtain a final pixel color.
84
85 Filter weights can be computed with several methods, for example:
86 - distance based filter weights (computed with MSFilterWeights)
87 - constant filter weights: 1/numSamples
88
89 However, a faster approach can be used where the MSAA texture is filtered onto a regular texture first,
90 followed by executing post processing shaders on that regular texture.
91 While this is not a correct MSAA implementation, it can give something close at better performance.
92 -> MSTextureSampler can be used to filter a MSAA texture onto a regular texture
93
94 Recommended resources on implementing MSAA with render to texture:
95 http://diaryofagraphicsprogrammer.blogspot.com/2009/06/multisample-anti-aliasing.html
96 http://www.humus.name/index.php?page=3D&ID=81
97 */
98
99 #ifdef GL_ARB_texture_multisample
100 #define MSFILTERWEIGHTS
101
102 class ACGDLLEXPORT MSFilterWeights
103 {
104 public:
105
106 MSFilterWeights(int _numSamples);
107
108 virtual ~MSFilterWeights() { }
109
110
111 // Initializes a texture buffer with filter weights in format GL_R32F.
112 // This can be used for reading from multisampled textures in a shader.
113 void asTextureBuffer(TextureBuffer& out);
114
115
116 // get ptr to weights as array, can be used for setUniform() for example
117 const float* asDataPtr() const {return &weights_[0];}
118
119
120 float operator [] (int i) const {return weights_[i];}
121
122 float getWeight(int i) const {return weights_[i];}
123
124 int getNumSamples() const {return numSamples_;}
125
126 private:
127
128 int numSamples_;
129 std::vector<float> weights_;
130 };
131
132 #endif // GL_ARB_texture_multisample
133
134
135
136
137 //== CLASS DEFINITION =========================================================
138
139
140 // This class performs multisampling on MSAA textures and writes the result to the currently bound FBO.
141 #ifdef GL_ARB_texture_multisample
142 #define MSTEXTURESAMPLER
143
144 class ACGDLLEXPORT MSTextureSampler
145 {
146 public:
147
148 ~MSTextureSampler();
149
150
151 // nearest point filtering of a MSAA texture, recommended when the target FBO has the same size as the input texture
152 static void filterMSAATexture_Nearest(GLuint _texture, int _samples, const float* _weights = 0);
153
154 // nearest point filtering of a MSAA texture, recommended when the target FBO has the same size as the input texture
155 // also resolves a multisampled depth texture into the depth target
156 static void filterMSAATexture_Nearest(GLuint _texture, GLuint _depthTexture, int _samples, const float* _weights = 0);
157
158 // bilinear filtering of a MSAA texture
159 static void filterMSAATexture_Linear(GLuint _texture, int _samples, const float* _weights = 0);
160
161 private:
162
163 MSTextureSampler();
164
165
166 void init();
167
168 // singleton instance
169 static MSTextureSampler& instance();
170
171
172 TextureBuffer filterWeights_;
173
174 // sampling shaders for nearest and bilinear texture filtering
175 GLSL::Program* shaderNearest_;
176 GLSL::Program* shaderNearestDepth_;
177 GLSL::Program* shaderLinear_;
178 };
179
180 #endif // GL_ARB_texture_multisample
181
182
183
184 // maybe add:
185 // - blitting of multisampled render buffers
186 // - automatic generation of MSAA variants of a post processing fragment shader
187 // - downsampling of supersampled FBOs
188
189 //=============================================================================
190 } // namespace ACG
191 //=============================================================================
192 #endif // ANTI_ALIASING_HH defined
193 //=============================================================================
GLSL
This namespace contains all the classes and functions for handling GLSL shader and program objects...
Definition: AntiAliasing.hh:66
ACG
Namespace providing different geometric functions concerning angles.
Definition: BaseObjectData.hh:68
GLSL::Program
GLSL program class.
Definition: GLSLShader.hh:211