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Takes a first shot at re[re,re]-implementing composite colour decoding.

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This commit is contained in:
Thomas Harte 2019-01-12 17:59:24 -05:00
parent 27541196cc
commit 25a1f23fc0
1 changed files with 82 additions and 42 deletions
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124
Outputs/OpenGL/ScanTargetGLSLFragments.cpp
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@ -428,7 +428,7 @@ std::unique_ptr<Shader> ScanTarget::composition_shader(InputDataType input_data_
}
std::unique_ptr<Shader> ScanTarget::conversion_shader(InputDataType input_data_type, DisplayType display_type, ColourSpace colour_space) {
display_type = DisplayType::CompositeMonochrome; // Just a test.
display_type = DisplayType::CompositeColour; // Just a test.
// Compose a vertex shader. If the display type is RGB, generate just the proper
// geometry position, plus a solitary textureCoordinate.
@ -526,7 +526,13 @@ std::unique_ptr<Shader> ScanTarget::conversion_shader(InputDataType input_data_t
break;
case DisplayType::CompositeColour:
// TODO
vertex_shader +=
"float centreCoordinate = mix(startClock, endClock, lateral);"
"float samplesPerAngle = (endClock - startClock) / (abs(endCompositeAngle - startCompositeAngle) / 32.0);"
"textureCoordinates[0] = vec2(centreCoordinate - 0.375*samplesPerAngle, lineY + 0.5) / textureSize(textureName, 0);"
"textureCoordinates[1] = vec2(centreCoordinate - 0.125*samplesPerAngle, lineY + 0.5) / textureSize(textureName, 0);"
"textureCoordinates[2] = vec2(centreCoordinate + 0.125*samplesPerAngle, lineY + 0.5) / textureSize(textureName, 0);"
"textureCoordinates[3] = vec2(centreCoordinate + 0.375*samplesPerAngle, lineY + 0.5) / textureSize(textureName, 0);";
break;
case DisplayType::SVideo:
@ -546,13 +552,52 @@ std::unique_ptr<Shader> ScanTarget::conversion_shader(InputDataType input_data_t
"uniform mat3 rgbToLumaChroma;";
}
if(display_type == DisplayType::CompositeMonochrome || display_type == DisplayType::CompositeColour) {
fragment_shader +=
"float composite_sample(vec2 coordinate, float angle) {";
switch(input_data_type) {
case InputDataType::Luminance1:
case InputDataType::Luminance8:
// Easy, just copy across.
fragment_shader += "return texture(textureName, coordinate).r;";
break;
case InputDataType::PhaseLinkedLuminance8:
fragment_shader +=
"uint iPhase = uint((angle * 2.0 / 3.141592654) ) & 3u;" // + phaseOffset*4.0
"return texture(textureName, coordinate)[iPhase];";
break;
case InputDataType::Luminance8Phase8:
fragment_shader +=
"vec2 yc = texture(textureName, coordinate).rg;"
"float phaseOffset = 3.141592654 * 2.0 * 2.0 * yc.y;"
"float rawChroma = step(yc.y, 0.75) * cos(angle + phaseOffset);"
"return mix(yc.x, yc.y * rawChroma, compositeAmplitude);";
break;
case InputDataType::Red1Green1Blue1:
case InputDataType::Red2Green2Blue2:
case InputDataType::Red4Green4Blue4:
case InputDataType::Red8Green8Blue8:
fragment_shader +=
"vec3 colour = rgbToLumaChroma * texture(textureName, coordinate).rgb;"
"vec2 quadrature = vec2(cos(angle), sin(angle));"
"return mix(colour.r, dot(quadrature, colour.gb), compositeAmplitude);";
break;
}
fragment_shader += "}";
}
fragment_shader +=
"void main(void) {"
"vec3 fragColour3;";
switch(display_type) {
case DisplayType::RGB:
// Easy, just copy across.
fragment_shader += "fragColour3 = texture(textureName, textureCoordinate).rgb;";
break;
@ -561,53 +606,48 @@ std::unique_ptr<Shader> ScanTarget::conversion_shader(InputDataType input_data_t
break;
case DisplayType::CompositeColour:
// TODO
fragment_shader +=
// Figure out the four composite angles. TODO: make these an input?
"vec4 angles = vec4("
"compositeAngle - 2.356194490192345,"
"compositeAngle - 0.785398163397448,"
"compositeAngle + 0.785398163397448,"
"compositeAngle + 2.356194490192345"
");"
// Sample four times over, at proper angle offsets.
"vec4 samples = vec4("
"composite_sample(textureCoordinates[0], angles[0]),"
"composite_sample(textureCoordinates[1], angles[1]),"
"composite_sample(textureCoordinates[2], angles[2]),"
"composite_sample(textureCoordinates[3], angles[3])"
");"
// Take the average to calculate luminance, then subtract that from all four samples to
// give chrominance.
"float luminance = dot(samples, vec4(0.25));"
"samples -= vec4(luminance);"
// Split and average chrominance.
"vec2 channels = vec2("
"dot(cos(angles), samples),"
"dot(sin(angles), samples)"
") / vec2(2.0);"
// Apply a colour space conversion to get RGB.
"fragColour3 = lumaChromaToRGB * vec3(luminance, channels);";
break;
case DisplayType::CompositeMonochrome: {
switch(input_data_type) {
case InputDataType::Luminance1:
case InputDataType::Luminance8:
// Easy, just copy across.
fragment_shader += "fragColour3 = texture(textureName, textureCoordinate).rgb;";
break;
case InputDataType::PhaseLinkedLuminance8:
fragment_shader +=
"uint iPhase = uint((compositeAngle * 2.0 / 3.141592654) ) & 3u;" // + phaseOffset*4.0
"fragColour3 = vec3(texture(textureName, textureCoordinate)[iPhase]);";
break;
case InputDataType::Luminance8Phase8:
fragment_shader +=
"vec2 yc = texture(textureName, textureCoordinate).rg;"
"float phaseOffset = 3.141592654 * 2.0 * 2.0 * yc.y;"
"float rawChroma = step(yc.y, 0.75) * cos(compositeAngle + phaseOffset);"
"float level = mix(yc.x, yc.y * rawChroma, compositeAmplitude);"
"fragColour3 = vec3(level);";
break;
case InputDataType::Red1Green1Blue1:
case InputDataType::Red2Green2Blue2:
case InputDataType::Red4Green4Blue4:
case InputDataType::Red8Green8Blue8:
fragment_shader +=
"vec3 colour = rgbToLumaChroma * texture(textureName, textureCoordinate).rgb;"
"vec2 quadrature = vec2(cos(compositeAngle), sin(compositeAngle));"
"float level = mix(colour.r, dot(quadrature, colour.gb), compositeAmplitude);"
"fragColour3 = vec3(level);";
break;
}
} break;
case DisplayType::CompositeMonochrome:
fragment_shader += "fragColour3 = vec3(composite_sample(textureCoordinate, compositeAngle));";
break;
}
// TODO gamma and range corrections.
fragment_shader +=
"fragColour = vec4(fragColour3, 0.64);"
"}";
// TODO gamma and range corrections.
const auto shader = new Shader(
vertex_shader,
fragment_shader,