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Discards empty lines, yet makes some attempt at restoring transparency.

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The two things conflict more than a little, so work to do.
This commit is contained in:
Thomas Harte 2018-11-15 21:51:27 -05:00
parent 5a31891048
commit 16dfeb3fc8
2 changed files with 26 additions and 11 deletions
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36
Outputs/OpenGL/ScanTarget.cpp
View File

@ -99,7 +99,7 @@ ScanTarget::ScanTarget() :
"uniform sampler2D textureName;"
"void main(void) {"
"fragColour = texture(textureName, textureCoordinate);"
"fragColour = vec4(texture(textureName, textureCoordinate).rgb, 0.64);"
"}"
));
@ -107,6 +107,9 @@ ScanTarget::ScanTarget() :
glBindBuffer(GL_ARRAY_BUFFER, line_buffer_name_);
enable_vertex_attributes(ShaderType::Line, *output_shader_);
glBlendFunc(GL_SRC_ALPHA, GL_CONSTANT_COLOR);
glBlendColor(0.4f, 0.4f, 0.4f, 1.0f);
is_drawing_.clear();
}
@ -190,6 +193,7 @@ Outputs::Display::ScanTarget::Scan *ScanTarget::begin_scan() {
return nullptr;
}
write_pointers_.scan_buffer = next_write_pointer;
++provided_scans_;
// Fill in extra OpenGL-specific details.
result->line = write_pointers_.line;
@ -286,21 +290,29 @@ void ScanTarget::announce(Event event, uint16_t x, uint16_t y) {
if(active_line_) {
active_line_->end_points[1].x = x;
active_line_->end_points[1].y = y;
active_line_ = nullptr;
}
break;
case ScanTarget::Event::EndHorizontalRetrace: {
const auto read_pointers = read_pointers_.load();
// Commit the most recent line only if any scans fell on it.
// Otherwise there's no point outputting it, it'll contribute nothing.
if(provided_scans_) {
const auto read_pointers = read_pointers_.load();
// Attempt to allocate a new line; note allocation failure if necessary.
const auto next_line = uint16_t((write_pointers_.line + 1) % LineBufferHeight);
// Attempt to allocate a new line; note allocation failure if necessary.
const auto next_line = uint16_t((write_pointers_.line + 1) % LineBufferHeight);
// Check whether that's too many.
if(next_line == read_pointers.line) {
allocation_has_failed_ = true;
} else {
write_pointers_.line = next_line;
active_line_ = &line_buffer_[size_t(write_pointers_.line)];
// Check whether that's too many.
if(next_line == read_pointers.line) {
allocation_has_failed_ = true;
active_line_ = nullptr;
} else {
write_pointers_.line = next_line;
active_line_ = &line_buffer_[size_t(write_pointers_.line)];
}
provided_scans_ = 0;
}
if(active_line_) {
active_line_->end_points[0].x = x;
active_line_->end_points[0].y = y;
active_line_->line = write_pointers_.line;
@ -437,6 +449,7 @@ void ScanTarget::draw(bool synchronous, int output_width, int output_height) {
// Push new input to the unprocessed line buffer.
if(new_scans) {
glDisable(GL_BLEND);
unprocessed_line_texture_.bind_framebuffer();
// Clear newly-touched lines; that is everything from (read+1) to submit.
@ -472,6 +485,7 @@ void ScanTarget::draw(bool synchronous, int output_width, int output_height) {
// Output all lines except the one currently being worked on.
glBindVertexArray(line_vertex_array_);
output_shader_->bind();
glEnable(GL_BLEND);
glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, GLsizei(line_buffer_.size() - 1));
// All data now having been spooled to the GPU, update the read pointers to

1
Outputs/OpenGL/ScanTarget.hpp
View File

@ -87,6 +87,7 @@ class ScanTarget: public Outputs::Display::ScanTarget {
std::array<Line, LineBufferHeight> line_buffer_;
TextureTarget unprocessed_line_texture_;
Line *active_line_ = nullptr;
int provided_scans_ = 0;
// OpenGL storage handles for buffer data.
GLuint scan_buffer_name_ = 0, scan_vertex_array_ = 0;