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GLSL cleanup: make var_FadeDepth a scalar #1338

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GLSL cleanup: make var_FadeDepth a scalar #1338

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11 changes: 9 additions & 2 deletions src/engine/renderer/glsl_source/generic_fp.glsl
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ IN(smooth) vec2 var_TexCoords;
IN(smooth) vec4 var_Color;

#if defined(USE_DEPTH_FADE)
IN(smooth) vec2 var_FadeDepth;
IN(smooth) float var_FadeDepth;
uniform sampler2D u_DepthMap;
#endif

Expand All @@ -55,7 +55,14 @@ void main()

#if defined(USE_DEPTH_FADE)
float depth = texture2D(u_DepthMap, gl_FragCoord.xy / r_FBufSize).x;
float fadeDepth = 0.5 * var_FadeDepth.x / var_FadeDepth.y + 0.5;

// convert z from normalized device coordinates [-1, 1]
// to window coordinates [0, 1]
float fadeDepth = 0.5 * var_FadeDepth + 0.5;

// HACK: the (distance from triangle to object behind it) / (shader's depthFade distance) ratio
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Why not linearize it then? I assume the different fading based on near/far plane etc. is not intended.

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Seemed like more effort than it's worth since I would have to plumb through the near/far values (which can apparently be different for every view) with a uniform. There's an r_zNear GLSL define, but it seems to have a tenuous (at best) connection with the value which is actually used.

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Yeah, zFar is supposed to cover the whole map in whatever direction, while zNear can change for portals. depthtile1_vp does this, albeit with r_zNear, but if it's discreet enough then it's fine as is I guess.

// is calculated by using (nonlinear) depth values instead of the correct world units, so the
// fade curve will be different depending on the distance to the viewer and znear/zfar
color.a *= smoothstep(gl_FragCoord.z, fadeDepth, depth);
#endif

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4 changes: 2 additions & 2 deletions src/engine/renderer/glsl_source/generic_vp.glsl
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Expand Up @@ -40,7 +40,7 @@ uniform mat4 u_ModelViewProjectionMatrix;

#if defined(USE_DEPTH_FADE)
uniform float u_DepthScale;
OUT(smooth) vec2 var_FadeDepth;
OUT(smooth) float var_FadeDepth;
#endif

OUT(smooth) vec2 var_TexCoords;
Expand Down Expand Up @@ -96,7 +96,7 @@ void main()
#if defined(USE_DEPTH_FADE)
// compute z of end of fading effect
vec4 fadeDepth = u_ModelViewProjectionMatrix * (position - u_DepthScale * vec4(LB.normal, 0.0));
var_FadeDepth = fadeDepth.zw;
var_FadeDepth = fadeDepth.z / fadeDepth.w;
#endif

var_Color = color;
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