began draft of internal node rendering structure

app/render/gl/functions.cpp

@@ -0,0 +1,116 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2019 Olive Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "functions.h"
+
+#include <QOpenGLFunctions>
+#include <QOpenGLVertexArrayObject>
+#include <QOpenGLBuffer>
+
+const GLfloat blit_vertices[] = {
+  -1.0f, -1.0f, 0.0f,
+  1.0f, -1.0f, 0.0f,
+  1.0f, 1.0f, 0.0f,
+
+  -1.0f, -1.0f, 0.0f,
+  -1.0f, 1.0f, 0.0f,
+  1.0f, 1.0f, 0.0f
+};
+
+const GLfloat blit_texcoords[] = {
+  0.0, 0.0,
+  1.0, 0.0,
+  1.0, 1.0,
+
+  0.0, 0.0,
+  0.0, 1.0,
+  1.0, 1.0
+};
+
+const GLfloat flipped_blit_texcoords[] = {
+  0.0, 1.0,
+  1.0, 1.0,
+  1.0, 0.0,
+
+  0.0, 1.0,
+  0.0, 0.0,
+  1.0, 0.0
+};
+
+/**
+ * @brief Set up texture parameters and mipmap for drawing
+ *
+ * Internal function used just before drawing to allow mipmapped bilinear filtering when drawing textures small.
+ *
+ * @param f
+ *
+ * Currently active QOpenGLFunctions object (use context()->functions() if unsure).
+ */
+void PrepareToDraw(QOpenGLFunctions* f) {
+  f->glGenerateMipmap(GL_TEXTURE_2D);
+  f->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+  f->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  f->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
+  f->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
+}
+
+void olive::gl::Blit(ShaderPtr pipeline, bool flipped, QMatrix4x4 matrix) {
+  // FIXME: is currentContext() reliable here?
+  QOpenGLFunctions* func = QOpenGLContext::currentContext()->functions();
+
+  PrepareToDraw(func);
+
+  QOpenGLVertexArrayObject m_vao;
+  m_vao.create();
+  m_vao.bind();
+
+  QOpenGLBuffer m_vbo;
+  m_vbo.create();
+  m_vbo.bind();
+  m_vbo.allocate(blit_vertices, 18 * sizeof(GLfloat));
+  m_vbo.release();
+
+  QOpenGLBuffer m_vbo2;
+  m_vbo2.create();
+  m_vbo2.bind();
+  m_vbo2.allocate(flipped ? flipped_blit_texcoords : blit_texcoords, 12 * sizeof(GLfloat));
+  m_vbo2.release();
+
+  pipeline->bind();
+
+  pipeline->setUniformValue("mvp_matrix", matrix);
+  pipeline->setUniformValue("texture", 0);
+
+  GLuint vertex_location = static_cast<GLuint>(pipeline->attributeLocation("a_position"));
+  m_vbo.bind();
+  func->glEnableVertexAttribArray(vertex_location);
+  func->glVertexAttribPointer(vertex_location, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
+  m_vbo.release();
+
+  GLuint tex_location = static_cast<GLuint>(pipeline->attributeLocation("a_texcoord"));
+  m_vbo2.bind();
+  func->glEnableVertexAttribArray(tex_location);
+  func->glVertexAttribPointer(tex_location, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
+  m_vbo2.release();
+
+  func->glDrawArrays(GL_TRIANGLES, 0, 6);
+
+  pipeline->release();
+}