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Started making the format of data included in a CRTFrame less a matter of variously hard-coded magic constants. Which will allow me to separate the idea of an internal lateral position from the direct texture coordinate, avoiding precision sampling errors at the top and bottom.
This commit is contained in:
Thomas Harte
parent
be421587ad
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3ab6585789
@ -11,6 +11,7 @@
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#import <OpenGL/gl3.h>
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#import <OpenGL/gl3ext.h>
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@implementation CSCathodeRayView {
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CVDisplayLinkRef displayLink;
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@ -19,6 +20,7 @@
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GLuint _arrayBuffer, _vertexArray;
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GLint _positionAttribute;
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GLint _textureCoordinatesAttribute;
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GLint _lateralAttribute;
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GLuint _textureName;
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CRTSize _textureSize;
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@ -128,7 +130,7 @@ static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
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if(crtFrame)
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{
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[self.openGLContext makeCurrentContext];
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glBufferData(GL_ARRAY_BUFFER, _crtFrame->number_of_runs * sizeof(GLushort) * 24, _crtFrame->runs, GL_DYNAMIC_DRAW);
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glBufferData(GL_ARRAY_BUFFER, _crtFrame->number_of_runs * sizeof(GLushort) * kCRTSizeOfVertex * 6, _crtFrame->runs, GL_DYNAMIC_DRAW);
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glBindTexture(GL_TEXTURE_2D, _textureName);
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@ -156,10 +158,12 @@ const char *vertexShader =
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"in vec2 srcCoordinates;\n"
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"\n"
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"out vec2 srcCoordinatesVarying;\n"
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"out float offsetVarying;\n"
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"\n"
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"void main (void)\n"
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"{\n"
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"srcCoordinatesVarying = vec2(srcCoordinates.x / 512.0, srcCoordinates.y / 512.0);\n"
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"offsetVarying = mod(srcCoordinatesVarying.y * 512, 1.0) * 2.09435310266667 + 0.52359877566668;"
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"gl_Position = vec4(position.x * 2.0 - 1.0, 1.0 - position.y * 2.0 + position.x / 131.0, 0.0, 1.0);\n"
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"}\n";
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@ -168,12 +172,13 @@ const char *fragmentShader =
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"#version 150\n"
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"\n"
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"in vec2 srcCoordinatesVarying;\n"
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"in float offsetVarying;"
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"out vec4 fragColour;\n"
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"uniform sampler2D texID;\n"
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"\n"
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"void main(void)\n"
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"{\n"
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"fragColour = texture(texID, srcCoordinatesVarying) * vec4(1.0, 1.0, 1.0, sin(mod(srcCoordinatesVarying.y * 512, 1.0) * 2.09435310266667 + 0.52359877566668));\n" // vec4(1.0, 1.0, 1.0, 0.5)
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"fragColour = texture(texID, srcCoordinatesVarying) * vec4(1.0, 1.0, 1.0, sin(offsetVarying));\n" // vec4(1.0, 1.0, 1.0, 0.5)
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"}\n";
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#if defined(DEBUG)
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@ -226,12 +231,16 @@ const char *fragmentShader =
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_positionAttribute = glGetAttribLocation(_shaderProgram, "position");
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_textureCoordinatesAttribute = glGetAttribLocation(_shaderProgram, "srcCoordinates");
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_lateralAttribute = glGetAttribLocation(_shaderProgram, "lateral");
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glEnableVertexAttribArray(_positionAttribute);
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glEnableVertexAttribArray(_textureCoordinatesAttribute);
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glEnableVertexAttribArray(_lateralAttribute);
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glVertexAttribPointer(_positionAttribute, 2, GL_UNSIGNED_SHORT, GL_TRUE, 4 * sizeof(GLushort), (void *)0);
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glVertexAttribPointer(_textureCoordinatesAttribute, 2, GL_UNSIGNED_SHORT, GL_FALSE, 4 * sizeof(GLushort), (void *)(2 * sizeof(GLushort)));
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const GLsizei vertexStride = kCRTSizeOfVertex * sizeof(GLushort);
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glVertexAttribPointer(_positionAttribute, 2, GL_UNSIGNED_SHORT, GL_TRUE, vertexStride, (void *)(kCRTVertexOffsetOfPosition * sizeof(GLushort)));
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glVertexAttribPointer(_textureCoordinatesAttribute, 2, GL_UNSIGNED_SHORT, GL_FALSE, vertexStride, (void *)(kCRTVertexOffsetOfTexCoord * sizeof(GLushort)));
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glVertexAttribPointer(_lateralAttribute, 1, GL_UNSIGNED_SHORT, GL_FALSE, vertexStride, (void *)(kCRTVertexOffsetOfLateral * sizeof(GLushort)));
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glGenTextures(1, &_textureName);
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glBindTexture(GL_TEXTURE_2D, _textureName);
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@ -20,8 +20,8 @@ static const uint32_t kCRTFixedPointOffset = 0x08000000;
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void CRT::set_new_timing(int cycles_per_line, int height_of_display)
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{
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const int syncCapacityLineChargeThreshold = 3;
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const int millisecondsHorizontalRetraceTime = 7; // source: Dictionary of Video and Television Technology, p. 234
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const int syncCapacityLineChargeThreshold = 4;
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const int millisecondsHorizontalRetraceTime = 10; // source: Dictionary of Video and Television Technology, p. 234
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const int scanlinesVerticalRetraceTime = 7; // source: ibid
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_time_multiplier = (1000 + cycles_per_line - 1) / cycles_per_line;
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@ -207,17 +207,23 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
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// uint32_t *width = _widths[lengthMask];
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uint32_t *width = _widths[0];
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#define position_x(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfPosition + 0]
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#define position_y(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfPosition + 1]
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#define tex_x(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfTexCoord + 0]
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#define tex_y(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfTexCoord + 1]
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#define lateral(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfLateral]
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if(next_run)
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{
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// set the type, initial raster position and type of this run
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next_run[0] = next_run[20] = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
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next_run[1] = next_run[21] = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
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next_run[4] = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
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next_run[5] = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
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position_x(0) = position_x(4) = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
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position_y(0) = position_y(4) = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
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position_x(1) = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
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position_y(1) = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
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next_run[2] = next_run[6] = next_run[22] = tex_x;
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next_run[3] = next_run[23] = tex_y;
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next_run[7] = tex_y + 1;
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tex_x(0) = tex_x(1) = tex_x(4) = tex_x;
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tex_y(0) = tex_y(4) = tex_y;
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tex_y(1) = tex_y + 1;
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}
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// advance the raster position as dictated by current sync status
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@ -234,19 +240,18 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
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if(next_run)
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{
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// store the final raster position
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next_run[8] = next_run[12] = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
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next_run[9] = next_run[13] = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
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next_run[16] = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
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next_run[17] = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
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position_x(2) = position_x(3) = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
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position_y(2) = position_y(3) = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
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position_x(5) = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
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position_y(5) = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
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// if this is a data run then advance the buffer pointer
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if(type == Type::Data) tex_x += next_run_length / _time_multiplier;
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// if this is a data or level run then store the end point
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next_run[10] = next_run[14] = next_run[18] = tex_x;
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next_run[11] = next_run[15] = tex_y + 1;
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next_run[19] = tex_y;
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tex_x(2) = tex_x(3) = tex_x(5) = tex_x;
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tex_y(2) = tex_y(3) = tex_y+1;
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tex_y(5) = tex_y;
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}
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// decrement the number of cycles left to run for and increment the
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@ -419,13 +424,16 @@ void CRTFrameBuilder::complete()
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uint16_t *CRTFrameBuilder::get_next_run()
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{
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const size_t vertices_per_run = 6;
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const size_t size_of_run = kCRTSizeOfVertex * vertices_per_run;
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// get a run from the allocated list, allocating more if we're about to overrun
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if(frame.number_of_runs * 24 >= _all_runs.size())
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if(frame.number_of_runs * size_of_run >= _all_runs.size())
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{
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_all_runs.resize(_all_runs.size() + 2400);
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_all_runs.resize(_all_runs.size() + size_of_run * 200);
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}
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uint16_t *next_run = &_all_runs[frame.number_of_runs * 24];
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uint16_t *next_run = &_all_runs[frame.number_of_runs * size_of_run];
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frame.number_of_runs++;
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return next_run;
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@ -36,4 +36,9 @@ typedef struct {
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}
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#endif
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static const int kCRTSizeOfVertex = 5;
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static const int kCRTVertexOffsetOfPosition = 0;
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static const int kCRTVertexOffsetOfTexCoord = 2;
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static const int kCRTVertexOffsetOfLateral = 4;
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#endif /* CRTFrame_h */
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