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50 lines
1.6 KiB
GLSL
50 lines
1.6 KiB
GLSL
#version 120
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//
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// metavoxel_heighfield_splat.vert
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// vertex shader
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//
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// Created by Andrzej Kapolka on 8/20/14.
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// Copyright 2014 High Fidelity, Inc.
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//
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// Distributed under the Apache License, Version 2.0.
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// See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
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//
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// the height texture
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uniform sampler2D heightMap;
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// the texture that contains the texture indices
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uniform sampler2D textureMap;
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// the distance between height points in texture space
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uniform float heightScale;
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// the scale between height and texture textures
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uniform float textureScale;
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// the lower bounds of the values corresponding to the splat textures
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uniform vec4 textureValueMinima;
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// the upper bounds of the values corresponding to the splat textures
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uniform vec4 textureValueMaxima;
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// alpha values for the four splat textures
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varying vec4 alphaValues;
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void main(void) {
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// add the height to the position
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float height = texture2D(heightMap, gl_MultiTexCoord0.st).r;
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gl_Position = gl_ModelViewProjectionMatrix * (gl_Vertex + vec4(0.0, height, 0.0, 0.0));
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// the zero height should be invisible
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gl_FrontColor = vec4(1.0, 1.0, 1.0, 1.0 - step(height, 0.0));
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// pass along the scaled/offset texture coordinates
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gl_TexCoord[0] = (gl_MultiTexCoord0 - vec4(heightScale, heightScale, 0.0, 0.0)) * textureScale;
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// compute the alpha values for each texture
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float value = texture2D(textureMap, gl_TexCoord[0].st).r;
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vec4 valueVector = vec4(value, value, value, value);
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alphaValues = step(textureValueMinima, valueVector) * step(valueVector, textureValueMaxima);
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}
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