Shuffles the OpenGL primitives into their own collection.

2026-04-23 14:25:11 +00:00 · 2018-11-07 19:11:01 -05:00
parent 55da1e9c0f
commit 7881e40e0b
7 changed files with 34 additions and 22 deletions
@@ -0,0 +1,146 @@
+//
+//  TextureTarget.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 07/02/2016.
+//  Copyright 2016 Thomas Harte. All rights reserved.
+//
+
+#include "TextureTarget.hpp"
+
+#include <cstdlib>
+#include <vector>
+
+using namespace OpenGL;
+
+TextureTarget::TextureTarget(GLsizei width, GLsizei height, GLenum texture_unit, GLint mag_filter) :
+		width_(width),
+		height_(height),
+		texture_unit_(texture_unit) {
+	glGenFramebuffers(1, &framebuffer_);
+	glBindFramebuffer(GL_FRAMEBUFFER, framebuffer_);
+
+	expanded_width_ = 1;
+	while(expanded_width_ < width)		expanded_width_ <<= 1;
+	expanded_height_ = 1;
+	while(expanded_height_ < height)	expanded_height_ <<= 1;
+
+	glGenTextures(1, &texture_);
+	bind_texture();
+
+	std::vector<uint8_t> blank_buffer(static_cast<size_t>(expanded_width_ * expanded_height_ * 4), 0);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, static_cast<GLsizei>(expanded_width_), static_cast<GLsizei>(expanded_height_), 0, GL_RGBA, GL_UNSIGNED_BYTE, blank_buffer.data());
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mag_filter);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+
+	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture_, 0);
+
+	if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
+		throw ErrorFramebufferIncomplete;
+}
+
+TextureTarget::~TextureTarget() {
+	glDeleteFramebuffers(1, &framebuffer_);
+	glDeleteTextures(1, &texture_);
+	if(drawing_vertex_array_) glDeleteVertexArrays(1, &drawing_vertex_array_);
+	if(drawing_array_buffer_) glDeleteBuffers(1, &drawing_array_buffer_);
+}
+
+void TextureTarget::bind_framebuffer() {
+	glBindFramebuffer(GL_FRAMEBUFFER, framebuffer_);
+	glViewport(0, 0, width_, height_);
+}
+
+void TextureTarget::bind_texture() {
+	glActiveTexture(texture_unit_);
+	glBindTexture(GL_TEXTURE_2D, texture_);
+}
+
+void TextureTarget::draw(float aspect_ratio, float colour_threshold) {
+	if(!pixel_shader_) {
+		const char *vertex_shader =
+			"#version 150\n"
+
+			"in vec2 texCoord;"
+			"in vec2 position;"
+
+			"out vec2 texCoordVarying;"
+
+			"void main(void)"
+			"{"
+				"texCoordVarying = texCoord;"
+				"gl_Position = vec4(position, 0.0, 1.0);"
+			"}";
+		const char *fragment_shader =
+			"#version 150\n"
+
+			"in vec2 texCoordVarying;"
+
+			"uniform sampler2D texID;"
+			"uniform float threshold;"
+
+			"out vec4 fragColour;"
+
+			"void main(void)"
+			"{"
+				"fragColour = clamp(texture(texID, texCoordVarying), threshold, 1.0);"
+			"}";
+		pixel_shader_.reset(new Shader(vertex_shader, fragment_shader));
+		pixel_shader_->bind();
+
+		glGenVertexArrays(1, &drawing_vertex_array_);
+		glGenBuffers(1, &drawing_array_buffer_);
+
+		glBindVertexArray(drawing_vertex_array_);
+		glBindBuffer(GL_ARRAY_BUFFER, drawing_array_buffer_);
+
+		GLint position_attribute	= pixel_shader_->get_attrib_location("position");
+		GLint tex_coord_attribute	= pixel_shader_->get_attrib_location("texCoord");
+
+		glEnableVertexAttribArray(static_cast<GLuint>(position_attribute));
+		glEnableVertexAttribArray(static_cast<GLuint>(tex_coord_attribute));
+
+		const GLsizei vertex_stride = 4 * sizeof(GLfloat);
+		glVertexAttribPointer((GLuint)position_attribute,	2, GL_FLOAT,	GL_FALSE,	vertex_stride,	(void *)0);
+		glVertexAttribPointer((GLuint)tex_coord_attribute,	2, GL_FLOAT,	GL_FALSE,	vertex_stride,	(void *)(2 * sizeof(GLfloat)));
+
+		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) {
+		set_aspect_ratio_ = aspect_ratio;
+		float buffer[4*4];
+
+		// establish texture coordinates
+		buffer[2] = 0.0f;
+		buffer[3] = 0.0f;
+		buffer[6] = 0.0f;
+		buffer[7] = static_cast<float>(height_) / static_cast<float>(expanded_height_);
+		buffer[10] = static_cast<float>(width_) / static_cast<float>(expanded_width_);
+		buffer[11] = 0.0f;
+		buffer[14] = buffer[10];
+		buffer[15] = buffer[7];
+
+		// determine positions; rule is to keep the same height and centre
+		float internal_aspect_ratio = static_cast<float>(width_) / static_cast<float>(height_);
+		float aspect_ratio_ratio = internal_aspect_ratio / aspect_ratio;
+
+		buffer[0] = -aspect_ratio_ratio;	buffer[1] = -1.0f;
+		buffer[4] = -aspect_ratio_ratio;	buffer[5] = 1.0f;
+		buffer[8] = aspect_ratio_ratio;		buffer[9] = -1.0f;
+		buffer[12] = aspect_ratio_ratio;	buffer[13] = 1.0f;
+
+		// upload buffer
+		glBindBuffer(GL_ARRAY_BUFFER, drawing_array_buffer_);
+		glBufferData(GL_ARRAY_BUFFER, sizeof(buffer), buffer, GL_STATIC_DRAW);
+	}
+
+	pixel_shader_->bind();
+	glUniform1f(threshold_uniform_, colour_threshold);
+
+	glBindVertexArray(drawing_vertex_array_);
+	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+}