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POOptimization of HLSL shader
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copied!<p>I have the problem that the below pixel shader (HLSL) compiles to <strong>68</strong> instructions (with the below suggested optimizations). However, I would like to use it with shader model 2 and therefore unfortunately I can only use up to <strong>64</strong> instructions. Does anyone see any possible optimizations without changing the result of the shader?</p> <p>The shader transforms a more-or-less spherical region of the screen (with sinus-shaped borders) from RGB to a gradient of white -> red -> black with some additional brightness etc. modifications.</p> <p>The shader code is: </p> <pre><code>// Normalized timefactor (1 = fully enabled) float timeFactor; // Center of "light" float x; float y; // Size of "light" float viewsizeQ; float fadesizeQ; // Rotational shift float angleShift; // Resolution float screenResolutionWidth; float screenResolutionHeight; float screenZoomQTimesX; // Texture sampler sampler TextureSampler : register(s0); float4 method(float2 texCoord : TEXCOORD0) : COLOR0 { // New color after transformation float4 newColor; // Look up the texture color. float4 color = tex2D(TextureSampler, texCoord); // Calculate distance float2 delta = (float2(x, y) - texCoord.xy) * float2(screenResolutionWidth, screenResolutionHeight); // Get angle from center float distQ = dot(delta, delta) - sin((atan2(delta.x, delta.y) + angleShift) * 13) * screenZoomQTimesX; // Within fadeSize if (distQ < fadesizeQ) { // Make greyscale float grey = dot(color.rgb, float3(0.3, 0.59, 0.11)); // Increase contrast by applying a color transformation based on a quasi-sigmoid gamma curve grey = 1 / (1 + pow(1.25-grey/2, 16) ); // Transform Black/White color range to Black/Red/White color range // 1 -> 0.5f ... White -> Red if (grey >= 0.75) { newColor.r = 0.7 + 0.3 * color.r; grey = (grey - 0.75) * 4; newColor.gb = 0.7 * grey + 0.3 * color.gb; } else // 0.5f -> 0 ... Red -> Black { newColor.r = 1.5 * 0.7 * grey + 0.3 * color.r; newColor.gb = 0.3 * color.gb ; } // Within viewSize (Full transformation, only blend with timefactor) if (distQ < viewsizeQ) { color.rgb = lerp(newColor.rgb, color.rgb, timeFactor); } // Outside viewSize but still in fadeSize (Spatial fade-out but also with timefactor) else { float factor = timeFactor * (1 - (distQ - viewsizeQ) / (fadesizeQ - viewsizeQ)); color.rgb = lerp(newColor.rgb, color.rgb, factor); } } </code></pre>

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