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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.

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This commit is contained in:
Thomas Harte 2015-08-02 14:25:21 -04:00
parent be421587ad
commit 3ab6585789
3 changed files with 46 additions and 24 deletions
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17
OSBindings/Mac/Clock Signal/CSCathodeRayView.m
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@ -11,6 +11,7 @@
#import <OpenGL/gl3.h>
#import <OpenGL/gl3ext.h>
@implementation CSCathodeRayView {
CVDisplayLinkRef displayLink;
@ -19,6 +20,7 @@
GLuint _arrayBuffer, _vertexArray;
GLint _positionAttribute;
GLint _textureCoordinatesAttribute;
GLint _lateralAttribute;
GLuint _textureName;
CRTSize _textureSize;
@ -128,7 +130,7 @@ static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
if(crtFrame)
{
[self.openGLContext makeCurrentContext];
glBufferData(GL_ARRAY_BUFFER, _crtFrame->number_of_runs * sizeof(GLushort) * 24, _crtFrame->runs, GL_DYNAMIC_DRAW);
glBufferData(GL_ARRAY_BUFFER, _crtFrame->number_of_runs * sizeof(GLushort) * kCRTSizeOfVertex * 6, _crtFrame->runs, GL_DYNAMIC_DRAW);
glBindTexture(GL_TEXTURE_2D, _textureName);
@ -156,10 +158,12 @@ const char *vertexShader =
"in vec2 srcCoordinates;\n"
"\n"
"out vec2 srcCoordinatesVarying;\n"
"out float offsetVarying;\n"
"\n"
"void main (void)\n"
"{\n"
"srcCoordinatesVarying = vec2(srcCoordinates.x / 512.0, srcCoordinates.y / 512.0);\n"
"offsetVarying = mod(srcCoordinatesVarying.y * 512, 1.0) * 2.09435310266667 + 0.52359877566668;"
"gl_Position = vec4(position.x * 2.0 - 1.0, 1.0 - position.y * 2.0 + position.x / 131.0, 0.0, 1.0);\n"
"}\n";
@ -168,12 +172,13 @@ const char *fragmentShader =
"#version 150\n"
"\n"
"in vec2 srcCoordinatesVarying;\n"
"in float offsetVarying;"
"out vec4 fragColour;\n"
"uniform sampler2D texID;\n"
"\n"
"void main(void)\n"
"{\n"
"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)
"fragColour = texture(texID, srcCoordinatesVarying) * vec4(1.0, 1.0, 1.0, sin(offsetVarying));\n" // vec4(1.0, 1.0, 1.0, 0.5)
"}\n";
#if defined(DEBUG)
@ -226,12 +231,16 @@ const char *fragmentShader =
_positionAttribute = glGetAttribLocation(_shaderProgram, "position");
_textureCoordinatesAttribute = glGetAttribLocation(_shaderProgram, "srcCoordinates");
_lateralAttribute = glGetAttribLocation(_shaderProgram, "lateral");
glEnableVertexAttribArray(_positionAttribute);
glEnableVertexAttribArray(_textureCoordinatesAttribute);
glEnableVertexAttribArray(_lateralAttribute);
glVertexAttribPointer(_positionAttribute, 2, GL_UNSIGNED_SHORT, GL_TRUE, 4 * sizeof(GLushort), (void *)0);
glVertexAttribPointer(_textureCoordinatesAttribute, 2, GL_UNSIGNED_SHORT, GL_FALSE, 4 * sizeof(GLushort), (void *)(2 * sizeof(GLushort)));
const GLsizei vertexStride = kCRTSizeOfVertex * sizeof(GLushort);
glVertexAttribPointer(_positionAttribute, 2, GL_UNSIGNED_SHORT, GL_TRUE, vertexStride, (void *)(kCRTVertexOffsetOfPosition * sizeof(GLushort)));
glVertexAttribPointer(_textureCoordinatesAttribute, 2, GL_UNSIGNED_SHORT, GL_FALSE, vertexStride, (void *)(kCRTVertexOffsetOfTexCoord * sizeof(GLushort)));
glVertexAttribPointer(_lateralAttribute, 1, GL_UNSIGNED_SHORT, GL_FALSE, vertexStride, (void *)(kCRTVertexOffsetOfLateral * sizeof(GLushort)));
glGenTextures(1, &_textureName);
glBindTexture(GL_TEXTURE_2D, _textureName);

48
Outputs/CRT.cpp
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@ -20,8 +20,8 @@ static const uint32_t kCRTFixedPointOffset = 0x08000000;
void CRT::set_new_timing(int cycles_per_line, int height_of_display)
{
const int syncCapacityLineChargeThreshold = 3;
const int millisecondsHorizontalRetraceTime = 7; // source: Dictionary of Video and Television Technology, p. 234
const int syncCapacityLineChargeThreshold = 4;
const int millisecondsHorizontalRetraceTime = 10; // source: Dictionary of Video and Television Technology, p. 234
const int scanlinesVerticalRetraceTime = 7; // source: ibid
_time_multiplier = (1000 + cycles_per_line - 1) / cycles_per_line;
@ -207,17 +207,23 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
// uint32_t *width = _widths[lengthMask];
uint32_t *width = _widths[0];
#define position_x(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfPosition + 0]
#define position_y(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfPosition + 1]
#define tex_x(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfTexCoord + 0]
#define tex_y(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfTexCoord + 1]
#define lateral(v) next_run[kCRTSizeOfVertex*v + kCRTVertexOffsetOfLateral]
if(next_run)
{
// set the type, initial raster position and type of this run
next_run[0] = next_run[20] = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
next_run[1] = next_run[21] = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
next_run[4] = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
next_run[5] = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
position_x(0) = position_x(4) = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
position_y(0) = position_y(4) = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
position_x(1) = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
position_y(1) = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
next_run[2] = next_run[6] = next_run[22] = tex_x;
next_run[3] = next_run[23] = tex_y;
next_run[7] = tex_y + 1;
tex_x(0) = tex_x(1) = tex_x(4) = tex_x;
tex_y(0) = tex_y(4) = tex_y;
tex_y(1) = tex_y + 1;
}
// advance the raster position as dictated by current sync status
@ -234,19 +240,18 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
if(next_run)
{
// store the final raster position
next_run[8] = next_run[12] = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
next_run[9] = next_run[13] = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
next_run[16] = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
next_run[17] = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
position_x(2) = position_x(3) = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
position_y(2) = position_y(3) = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
position_x(5) = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
position_y(5) = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
// if this is a data run then advance the buffer pointer
if(type == Type::Data) tex_x += next_run_length / _time_multiplier;
// if this is a data or level run then store the end point
next_run[10] = next_run[14] = next_run[18] = tex_x;
next_run[11] = next_run[15] = tex_y + 1;
next_run[19] = tex_y;
tex_x(2) = tex_x(3) = tex_x(5) = tex_x;
tex_y(2) = tex_y(3) = tex_y+1;
tex_y(5) = tex_y;
}
// decrement the number of cycles left to run for and increment the
@ -419,13 +424,16 @@ void CRTFrameBuilder::complete()
uint16_t *CRTFrameBuilder::get_next_run()
{
const size_t vertices_per_run = 6;
const size_t size_of_run = kCRTSizeOfVertex * vertices_per_run;
// get a run from the allocated list, allocating more if we're about to overrun
if(frame.number_of_runs * 24 >= _all_runs.size())
if(frame.number_of_runs * size_of_run >= _all_runs.size())
{
_all_runs.resize(_all_runs.size() + 2400);
_all_runs.resize(_all_runs.size() + size_of_run * 200);
}
uint16_t *next_run = &_all_runs[frame.number_of_runs * 24];
uint16_t *next_run = &_all_runs[frame.number_of_runs * size_of_run];
frame.number_of_runs++;
return next_run;

5
Outputs/CRTFrame.h
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@ -36,4 +36,9 @@ typedef struct {
}
#endif
static const int kCRTSizeOfVertex = 5;
static const int kCRTVertexOffsetOfPosition = 0;
static const int kCRTVertexOffsetOfTexCoord = 2;
static const int kCRTVertexOffsetOfLateral = 4;
#endif /* CRTFrame_h */