From 7fbe0814d52ba861a02b0560d4e6872845ef241e Mon Sep 17 00:00:00 2001
From: ccolin
Date: Tue, 22 Dec 2020 13:15:23 +0100
Subject: initial commit

---
 src/opengl_widget.cc | 143 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)
 create mode 100644 src/opengl_widget.cc

(limited to 'src/opengl_widget.cc')

diff --git a/src/opengl_widget.cc b/src/opengl_widget.cc
new file mode 100644
index 0000000..0251491
--- /dev/null
+++ b/src/opengl_widget.cc
@@ -0,0 +1,143 @@
+#include "opengl_widget.hh"
+
+
+static const GLchar *vertex_shader_source = R"glsl(
+#version 330 core
+
+layout(location = 0) in vec3 pos;
+
+uniform mat4 proj;
+uniform mat4 view;
+uniform mat4 model;
+
+void main() {
+	gl_Position = proj * view * model * vec4(pos, 1.0);
+}
+)glsl";
+
+static const GLchar *fragment_shader_source = R"glsl(
+#version 330 core
+
+out vec4 final_col;
+
+void main() {
+	final_col = vec4(0, 0, 0, 1);
+}
+)glsl";
+
+
+static void GLAPIENTRY opengl_debug_cb(GLenum source, GLenum type, GLuint id,
+									   GLenum severity, GLsizei length,
+									   const GLchar* message,
+									   const void* userParam) {
+	(void) source; (void) type; (void) id; (void) severity; (void) length;
+	(void) userParam;
+	qDebug() << "OpenGL debug output:" << message;
+}
+
+
+OpenGLWidget *OpenGLWidget::instance = nullptr;
+
+
+OpenGLWidget::OpenGLWidget(QWidget *parent)
+	:QOpenGLWidget(parent) {
+	OpenGLWidget::instance = this;
+}
+
+
+OpenGLWidget::~OpenGLWidget() {
+	OpenGLWidget::instance = nullptr;
+}
+
+
+void OpenGLWidget::initializeGL() {
+	initializeOpenGLFunctions();
+	GLint major, minor;
+	glGetIntegerv(GL_MAJOR_VERSION, &major);
+	glGetIntegerv(GL_MINOR_VERSION, &minor);
+	qDebug("OpenGL version %d.%d", major, minor);
+
+	glEnable(GL_DEBUG_OUTPUT);
+	glDebugMessageCallback(opengl_debug_cb, 0);
+
+	/* Compile the vertex shader. */
+	GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
+	glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
+	glCompileShader(vertex_shader);
+	GLint status;
+	glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &status);
+	if (status != GL_TRUE) {
+		char log[1024];
+		glGetShaderInfoLog(vertex_shader, sizeof log, NULL, log);
+		fprintf(stderr, "Failed to compile the vertex shader: %s\n", log);
+		exit(1);
+	}
+
+	/* Compile the fragment shader. */
+	GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
+	glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
+	glCompileShader(fragment_shader);
+	glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &status);
+	if (status != GL_TRUE) {
+		char log[1024];
+		glGetShaderInfoLog(fragment_shader, sizeof log, NULL, log);
+		fprintf(stderr, "Failed to compile the fragment shader: %s\n", log);
+		exit(1);
+	}
+
+	/* Link the shader program. */
+	GLuint shader_program = glCreateProgram();
+	glAttachShader(shader_program, vertex_shader);
+	glAttachShader(shader_program, fragment_shader);
+	glBindFragDataLocation(shader_program, 0, "out_color");
+	glLinkProgram(shader_program);
+	glGetProgramiv(shader_program, GL_LINK_STATUS, &status);
+	if (status != GL_TRUE) {
+		char log[1024];
+		glGetProgramInfoLog(shader_program, sizeof log, NULL, log);
+		fprintf(stderr, "Failed to link the shader program: %s\n", log);
+		exit(1);
+	}
+
+	/* Use it. */
+	glUseProgram(shader_program);
+
+	/* Get the position attribute. */
+	pos_attr = glGetAttribLocation(shader_program, "pos");
+
+	proj_attr = glGetUniformLocation(shader_program, "proj");
+	view_attr = glGetUniformLocation(shader_program, "view");
+	model_attr = glGetUniformLocation(shader_program, "model");
+
+	QMatrix4x4 view;
+	view.translate(0, 0, 5);
+	glUniformMatrix4fv(view_attr, 1, GL_FALSE, view.data());
+
+	QMatrix4x4 trans;
+	trans.translate(0, 0, -5);
+	glUniformMatrix4fv(view_attr, 1, GL_FALSE, trans.data());
+
+	glClearColor(1, 1, 1, 0);
+
+	glEnable(GL_DEPTH_TEST);
+	glEnable(GL_MULTISAMPLE);
+
+	emit initialized();
+}
+
+
+void OpenGLWidget::resizeGL(int w, int h) {
+	QMatrix4x4 projection;
+	projection.perspective(FOV, (float) w/h, .1, 100);
+	glUniformMatrix4fv(proj_attr, 1, GL_FALSE, projection.data());
+}
+
+
+void OpenGLWidget::paintGL() {
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	for (const OpenGLMesh &mesh : meshes) {
+		glUniformMatrix4fv(model_attr, 1, GL_FALSE, mesh.mat.data());
+		glBindVertexArray(mesh.vao);
+		glDrawArrays(GL_TRIANGLES, 0, mesh.nverts);
+	}
+}
-- 
cgit v1.2.3-70-g09d2