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Bites the bullet and accepts that an additional texture will be useful for QAM separation.

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Thomas Harte
2019-02-09 16:54:31 -05:00
parent 75987f64ec
commit eecd4417e7
3 changed files with 323 additions and 135 deletions
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Outputs/OpenGL/ScanTarget.cpp
+46 -8
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@@ -24,7 +24,14 @@ constexpr GLenum SourceDataTextureUnit = GL_TEXTURE0;
constexpr GLenum UnprocessedLineBufferTextureUnit = GL_TEXTURE1;
/// The texture unit that contains the current display.
constexpr GLenum AccumulationTextureUnit = GL_TEXTURE2;
constexpr GLenum AccumulationTextureUnit = GL_TEXTURE3;
/// The texture unit that contains a pre-lowpass-filtered but fixed-resolution version of the chroma signal;
/// this is used when processing composite video only, and for chroma information only. Luminance is calculated
/// at the fidelity permitted by the output target, but my efforts to separate, demodulate and filter
/// chrominance during output without either massively sampling or else incurring significant high-frequency
/// noise that sampling reduces into a Moire, have proven to be unsuccessful for the time being.
constexpr GLenum QAMChromaTextureUnit = GL_TEXTURE2;
#define TextureAddress(x, y) (((y) << 11) | (x))
#define TextureAddressGetY(v) uint16_t((v) >> 11)
@@ -299,9 +306,23 @@ void ScanTarget::setup_pipeline() {
write_pointers_.write_area = 0;
}
// Pick a processing width; this will be the minimum necessary not to
// lose any detail when combining the input.
processing_width_ = modals_.cycles_per_line / modals_.clocks_per_pixel_greatest_common_divisor;
// Destroy or create a QAM buffer and shader, if appropriate.
const bool needs_qam_buffer = (modals_.display_type == DisplayType::CompositeColour || modals_.display_type == DisplayType::SVideo);
if(needs_qam_buffer && !qam_chroma_texture_) {
qam_chroma_texture_.reset(new TextureTarget(LineBufferWidth, LineBufferHeight, QAMChromaTextureUnit, GL_NEAREST, false));
} else {
qam_chroma_texture_.reset();
qam_separation_shader_.reset();
}
if(needs_qam_buffer) {
qam_separation_shader_ = qam_separation_shader();
glBindVertexArray(line_vertex_array_);
glBindBuffer(GL_ARRAY_BUFFER, line_buffer_name_);
enable_vertex_attributes(ShaderType::QAMSeparation, *qam_separation_shader_);
set_uniforms(ShaderType::QAMSeparation, *qam_separation_shader_);
qam_separation_shader_->set_uniform("textureName", GLint(UnprocessedLineBufferTextureUnit - GL_TEXTURE0));
}
// Establish an output shader.
output_shader_ = conversion_shader();
@@ -312,6 +333,7 @@ void ScanTarget::setup_pipeline() {
output_shader_->set_uniform("origin", modals_.visible_area.origin.x, modals_.visible_area.origin.y);
output_shader_->set_uniform("size", modals_.visible_area.size.width, modals_.visible_area.size.height);
output_shader_->set_uniform("textureName", GLint(UnprocessedLineBufferTextureUnit - GL_TEXTURE0));
output_shader_->set_uniform("qamTextureName", GLint(QAMChromaTextureUnit - GL_TEXTURE0));
// Establish an input shader.
input_shader_ = composition_shader();
@@ -487,8 +509,10 @@ void ScanTarget::draw(bool synchronous, int output_width, int output_height) {
// Figure out how many new spans are ostensible ready; use two less than that.
uint16_t new_spans = (submit_pointers.line + LineBufferHeight - read_pointers.line) % LineBufferHeight;
if(new_spans) {
// Bind the accumulation framebuffer.
accumulation_texture_->bind_framebuffer();
// Bind the accumulation framebuffer, unless there's going to be QAM work.
if(!qam_separation_shader_) {
accumulation_texture_->bind_framebuffer();
}
// Enable blending and stenciling, and ensure spans increment the stencil buffer.
glEnable(GL_BLEND);
@@ -525,10 +549,12 @@ void ScanTarget::draw(bool synchronous, int output_width, int output_height) {
// Rebind the program for span output.
glBindVertexArray(line_vertex_array_);
output_shader_->bind();
if(!qam_separation_shader_) {
output_shader_->bind();
}
}
// Upload and draw.
// Upload.
const auto buffer_size = spans * sizeof(Line);
if(!end_line || end_line > start_line) {
glBufferSubData(GL_ARRAY_BUFFER, 0, GLsizeiptr(buffer_size), &line_buffer_[start_line]);
@@ -547,6 +573,18 @@ void ScanTarget::draw(bool synchronous, int output_width, int output_height) {
glUnmapBuffer(GL_ARRAY_BUFFER);
}
// Produce colour information, if required.
if(qam_separation_shader_) {
qam_chroma_texture_->bind_framebuffer();
qam_separation_shader_->bind();
glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, GLsizei(spans));
accumulation_texture_->bind_framebuffer();
output_shader_->bind();
}
// Render to the output.
glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, GLsizei(spans));
start_line = end_line;