40 lines
1.5 KiB
GLSL
40 lines
1.5 KiB
GLSL
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// written by groverbuger for g3d
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// september 2021
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// MIT license
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// this vertex shader is what projects 3d vertices in models onto your 2d screen
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uniform mat4 projectionMatrix; // handled by the camera
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uniform mat4 viewMatrix; // handled by the camera
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uniform mat4 modelMatrix; // models send their own model matrices when drawn
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uniform bool isCanvasEnabled; // detect when this model is being rendered to a canvas
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// the vertex normal attribute must be defined, as it is custom unlike the other attributes
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attribute vec3 VertexNormal;
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// define some varying vectors that are useful for writing custom fragment shaders
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varying vec4 worldPosition;
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varying vec4 viewPosition;
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varying vec4 screenPosition;
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varying vec3 vertexNormal;
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varying vec4 vertexColor;
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vec4 position(mat4 transformProjection, vec4 vertexPosition) {
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// calculate the positions of the transformed coordinates on the screen
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// save each step of the process, as these are often useful when writing custom fragment shaders
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worldPosition = modelMatrix * vertexPosition;
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viewPosition = viewMatrix * worldPosition;
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screenPosition = projectionMatrix * viewPosition;
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// save some data from this vertex for use in fragment shaders
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vertexNormal = VertexNormal;
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vertexColor = VertexColor;
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// for some reason models are flipped vertically when rendering to a canvas
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// so we need to detect when this is being rendered to a canvas, and flip it back
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if (isCanvasEnabled) {
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screenPosition.y *= -1.0;
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}
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return screenPosition;
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}
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