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Hides persistent low-part colour channel errors.

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This commit is contained in:
Thomas Harte 2018-06-14 20:40:27 -04:00
parent 1bd6bbca8d
commit b899a22c7d
3 changed files with 23 additions and 5 deletions
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5
Outputs/CRT/Internals/CRTOpenGL.cpp
View File

@ -238,14 +238,15 @@ void OpenGLOutputBuilder::draw_frame(unsigned int output_width, unsigned int out
// glTextureBarrierNV();
#endif
// copy framebuffer to the intended place
// Copy framebuffer to the intended place; apply a threshold so that any persistent errors in
// the lower part of the colour channels are invisible.
glDisable(GL_BLEND);
glBindFramebuffer(GL_FRAMEBUFFER, static_cast<GLuint>(target_framebuffer_));
glViewport(0, 0, (GLsizei)output_width, (GLsizei)output_height);
glActiveTexture(pixel_accumulation_texture_unit);
framebuffer_->bind_texture();
framebuffer_->draw(static_cast<float>(output_width) / static_cast<float>(output_height));
framebuffer_->draw(static_cast<float>(output_width) / static_cast<float>(output_height), 4.0f / 255.0f);
fence_ = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
draw_mutex_.unlock();

11
Outputs/CRT/Internals/TextureTarget.cpp
View File

@ -56,7 +56,7 @@ void TextureTarget::bind_texture() {
glBindTexture(GL_TEXTURE_2D, texture_);
}
void TextureTarget::draw(float aspect_ratio) {
void TextureTarget::draw(float aspect_ratio, float colour_threshold) {
if(!pixel_shader_) {
const char *vertex_shader =
"#version 150\n"
@ -75,12 +75,15 @@ void TextureTarget::draw(float aspect_ratio) {
"#version 150\n"
"in vec2 texCoordVarying;"
"uniform sampler2D texID;"
"uniform float threshold;"
"out vec4 fragColour;"
"void main(void)"
"{"
"fragColour = texture(texID, texCoordVarying);"
"fragColour = clamp(texture(texID, texCoordVarying), threshold, 1.0);"
"}";
pixel_shader_.reset(new Shader(vertex_shader, fragment_shader));
pixel_shader_->bind();
@ -103,6 +106,8 @@ void TextureTarget::draw(float aspect_ratio) {
GLint texIDUniform = pixel_shader_->get_uniform_location("texID");
glUniform1i(texIDUniform, static_cast<GLint>(texture_unit_ - GL_TEXTURE0));
threshold_uniform_ = pixel_shader_->get_uniform_location("threshold");
}
if(set_aspect_ratio_ != aspect_ratio) {
@ -134,6 +139,8 @@ void TextureTarget::draw(float aspect_ratio) {
}
pixel_shader_->bind();
glUniform1f(threshold_uniform_, colour_threshold);
glBindVertexArray(drawing_vertex_array_);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}

12
Outputs/CRT/Internals/TextureTarget.hpp
View File

@ -58,9 +58,17 @@ class TextureTarget {
}
/*!
Draws this texture to the currently-bound framebuffer, which has the aspect ratio
@c aspect_ratio. This texture will fill the height of the frame buffer, and pick
an appropriate width based o the aspect ratio.
@c colour_threshold sets a threshold test that each colour must satisfy to be
output. A threshold of 0.0f means that all colours will pass through. A threshold
of 0.5f means that only colour components above 0.5f will pass through, with
0.5f being substituted elsewhere. This provides a way to ensure that the sort of
persistent low-value errors that can result from an IIR are hidden.
*/
void draw(float aspect_ratio);
void draw(float aspect_ratio, float colour_threshold = 0.0f);
enum {
ErrorFramebufferIncomplete
@ -75,6 +83,8 @@ class TextureTarget {
std::unique_ptr<Shader> pixel_shader_;
GLuint drawing_vertex_array_ = 0, drawing_array_buffer_ = 0;
float set_aspect_ratio_ = 0.0f;
GLint threshold_uniform_;
};
}