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Started sketching out an appropriate interface to transfer responsibility for shaders to the CRT.

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This commit is contained in:
Thomas Harte 2016-01-23 19:06:32 -05:00
parent ace331d4b4
commit 1819e7b9cc
2 changed files with 97 additions and 0 deletions
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69
Outputs/CRT.cpp
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@ -519,3 +519,72 @@ uint8_t *CRTFrameBuilder::get_write_target_for_buffer(int buffer)
{
return &frame.buffers[buffer].data[_write_target_pointer * frame.buffers[buffer].depth];
}
char *CRT::get_vertex_shader()
{
// the main job of the vertex shader is just to map from an input area of [0,1]x[0,1], with the origin in the
// top left to OpenGL's [-1,1]x[-1,1] with the origin in the lower left, and to convert input data coordinates
// from integral to floating point; there's also some setup for NTSC, PAL or whatever.
const char *const ntscVertexShaderGlobals =
"out vec2 srcCoordinatesVarying[4];\n"
"out float phase;\n";
const char *const ntscVertexShaderBody =
"phase = srcCoordinates.x * 6.283185308;\n"
"\n"
"srcCoordinatesVarying[0] = vec2(srcCoordinates.x / textureSize.x, (srcCoordinates.y + 0.5) / textureSize.y);\n"
"srcCoordinatesVarying[3] = srcCoordinatesVarying[0] + vec2(0.375 / textureSize.x, 0.0);\n"
"srcCoordinatesVarying[2] = srcCoordinatesVarying[0] + vec2(0.125 / textureSize.x, 0.0);\n"
"srcCoordinatesVarying[1] = srcCoordinatesVarying[0] - vec2(0.125 / textureSize.x, 0.0);\n"
"srcCoordinatesVarying[0] = srcCoordinatesVarying[0] - vec2(0.325 / textureSize.x, 0.0);\n";
const char *const rgbVertexShaderGlobals =
"out vec2 srcCoordinatesVarying[5];\n";
const char *const rgbVertexShaderBody =
"srcCoordinatesVarying[2] = vec2(srcCoordinates.x / textureSize.x, (srcCoordinates.y + 0.5) / textureSize.y);\n"
"srcCoordinatesVarying[0] = srcCoordinatesVarying[1] - vec2(1.0 / textureSize.x, 0.0);\n"
"srcCoordinatesVarying[1] = srcCoordinatesVarying[1] - vec2(0.5 / textureSize.x, 0.0);\n"
"srcCoordinatesVarying[3] = srcCoordinatesVarying[1] + vec2(0.5 / textureSize.x, 0.0);\n"
"srcCoordinatesVarying[4] = srcCoordinatesVarying[1] + vec2(1.0 / textureSize.x, 0.0);\n";
const char *const vertexShader =
"#version 150\n"
"\n"
"in vec2 position;\n"
"in vec2 srcCoordinates;\n"
"in float lateral;\n"
"\n"
"uniform vec2 boundsOrigin;\n"
"uniform vec2 boundsSize;\n"
"\n"
"out float lateralVarying;\n"
"out vec2 shadowMaskCoordinates;\n"
"\n"
"uniform vec2 textureSize;\n"
"\n"
"const float shadowMaskMultiple = 600;\n"
"\n"
"%@\n"
"void main (void)\n"
"{\n"
"lateralVarying = lateral + 1.0707963267949;\n"
"\n"
"shadowMaskCoordinates = position * vec2(shadowMaskMultiple, shadowMaskMultiple * 0.85057471264368);\n"
"\n"
"%@\n"
"\n"
"vec2 mappedPosition = (position - boundsOrigin) / boundsSize;"
"gl_Position = vec4(mappedPosition.x * 2.0 - 1.0, 1.0 - mappedPosition.y * 2.0, 0.0, 1.0);\n"
"}\n";
return nullptr;
// + mappedPosition.x / 131.0
// switch(_signalType)
// {
// case CSCathodeRayViewSignalTypeNTSC: return [NSString stringWithFormat:vertexShader, ntscVertexShaderGlobals, ntscVertexShaderBody];
// case CSCathodeRayViewSignalTypeRGB: return [NSString stringWithFormat:vertexShader, rgbVertexShaderGlobals, rgbVertexShaderBody];
// }
}

28
Outputs/CRT.hpp
View File

@ -111,6 +111,34 @@ class CRT {
void allocate_write_area(int required_length);
uint8_t *get_write_target_for_buffer(int buffer);
/*! Gets the vertex shader for display of vended CRTFrames.
@returns A vertex shader, allocated using a C function. The caller then owns the memory
and is responsible for free'ing it.
*/
char *get_vertex_shader();
/*! Gets a fragment shader for display of vended CRTFrames based on the supplied sampling function.
@param sample_function A GLSL fragment including a function with the signature
`float sample(vec2 coordinate, float phase)` that evaluates to the composite signal level
as a function of a source buffer sampling location and the current colour carrier phase.
@returns A complete fragment shader.
*/
char *get_fragment_shader(const char *sample_function);
/*! Gets a fragment shader for composite display of vended CRTFrames based on a default encoding
of the supplied sampling function.
@param sample_function A GLSL fragent including a function with the signature
`vec3 sample(vec2 coordinate)` that evaluates to an RGB colour as a function of
the source buffer sampling location.
@returns A complete fragment shader.
*/
char *get_rgb_encoding_fragment_shader(const char *sample_function);
private:
CRT();
void allocate_buffers(unsigned int number, va_list sizes);