Add some OpenGL-related notes and hacks.

3 files changed, 386 insertions, 0 deletions

diff --git a/hacks/gl-notes b/hacks/gl-notes
new file mode 100644
index 000000000..0b1b11c2e
--- /dev/null
+++ b/hacks/gl-notes
@@ -0,0 +1,17 @@
+4.3 with compute shaders "came out in 2012"
+Anything before 3.0 is deprecated (especially anything with glBegin/glEnd)
+
+https://stackoverflow.com/questions/14300569/opengl-glbegin-glend
+"The direct mode API with glBegin and glEnd is deprecated, largely for performance reasons."
+"Using VBOs scales better"
+
+OpenGL 3.3 tutorials (written 2012)
+http://www.opengl-tutorial.org/
+
+An intro to modern OpenGL (written 2010)
+https://duriansoftware.com/joe/an-intro-to-modern-opengl.-table-of-contents
+
+Learning Modern 3D Graphics Programming (written 2012)
+https://web.archive.org/web/20140209181347/http://www.arcsynthesis.org/gltut/
+
+"Since OpenGL3.3 most old stuff was moved to compatibility profile, while modern features are core profile; the latter requires self-written shaders, but they should be pretty simple for your case).
diff --git a/hacks/gl/modern.cc b/hacks/gl/modern.cc
new file mode 100644
index 000000000..748547e47
--- /dev/null
+++ b/hacks/gl/modern.cc
@@ -0,0 +1,319 @@
+#include <QtGui/QGuiApplication>
+#include <QtGui/QKeyEvent>
+#include <QtGui/QOpenGLWindow>
+#include <QtGui/QOpenGLBuffer>
+#include <QtGui/QOpenGLFunctions>
+#include <QtGui/QOpenGLShaderProgram>
+#include <QtGui/QOpenGLVertexArrayObject>
+static QString vertexShader =
+"#version 100\n"
+"\n"
+"attribute vec3 vertexPosition;\n"
+"attribute vec3 vertexNormal;\n"
+"attribute vec3 vertexColor;\n"
+"attribute vec2 texCoord2d;\n"
+"\n"
+"uniform mat4 modelViewMatrix;\n"
+"uniform mat3 normalMatrix;\n"
+"uniform mat4 projectionMatrix;\n"
+"\n"
+"struct LightSource\n"
+"{\n"
+"    vec3 ambient;\n"
+"    vec3 diffuse;\n"
+"    vec3 specular;\n"
+"    vec3 position;\n"
+"};\n"
+"uniform LightSource lightSource;\n"
+"\n"
+"struct LightModel\n"
+"{\n"
+"    vec3 ambient;\n"
+"};\n"
+"uniform LightModel lightModel;\n"
+"\n"
+"struct Material {\n"
+"    vec3  emission;\n"
+"    vec3  specular;\n"
+"    float shininess;\n"
+"};\n"
+"uniform Material material;\n"
+"\n"
+"varying vec3 v_color;\n"
+"varying vec2 v_texCoord2d;\n"
+"\n"
+"void main()\n"
+"{\n"
+"    vec3 normal     = normalize(normalMatrix * vertexNormal);                       // normal vector              \n"
+"    vec3 position   = vec3(modelViewMatrix * vec4(vertexPosition, 1));              // vertex pos in eye coords   \n"
+"    vec3 halfVector = normalize(lightSource.position + vec3(0,0,1));                // light half vector          \n"
+"    float nDotVP    = dot(normal, normalize(lightSource.position));                 // normal . light direction   \n"
+"    float nDotHV    = max(0.f, dot(normal,  halfVector));                           // normal . light half vector \n"
+"    float pf        = mix(0.f, pow(nDotHV, material.shininess), step(0.f, nDotVP)); // power factor               \n"
+"\n"
+"    vec3 ambient    = lightSource.ambient;\n"
+"    vec3 diffuse    = lightSource.diffuse * nDotVP;\n"
+"    vec3 specular   = lightSource.specular * pf;\n"
+"    vec3 sceneColor = material.emission + vertexColor * lightModel.ambient;\n"
+"\n"
+"    v_color = clamp(sceneColor +                             \n"
+"                    ambient  * vertexColor +                 \n"
+"                    diffuse  * vertexColor +                 \n"
+"                    specular * material.specular, 0.f, 1.f );\n"
+"\n"
+"    v_texCoord2d = texCoord2d;\n"
+"\n"
+"    gl_Position = projectionMatrix * modelViewMatrix * vec4(vertexPosition, 1);\n"
+"}\n"
+;
+static QString fragmentShader =
+"#version 100\n"
+"precision lowp vec3;\n"
+"precision lowp vec2;\n"
+"uniform sampler2D texUnit;\n"
+"\n"
+"varying vec3 v_color;\n"
+"varying vec2 v_texCoord2d;\n"
+"\n"
+"void main()\n"
+"{\n"
+"    gl_FragColor = vec4(v_color, 1) * texture2D(texUnit, v_texCoord2d);\n"
+"}\n"
+;
+/*
+* Texture copied and modifided modified from:
+* <a href="https://www.opengl.org/archives/resources/code/samples/mjktips/TexShadowReflectLight.html
+*/
+static char *circles[] = {
+"................",
+"................",
+"......xxxx......",
+"....xxxxxxxx....",
+"...xxxxxxxxxx...",
+"...xxx....xxx...",
+"..xxx......xxx..",
+"..xxx......xxx..",
+"..xxx......xxx..",
+"..xxx......xxx..",
+"...xxx....xxx...",
+"...xxxxxxxxxx...",
+"....xxxxxxxx....",
+"......xxxx......",
+"................",
+"................",
+};
+struct Window : QOpenGLWindow, QOpenGLFunctions
+{
+Window() :
+m_vbo(QOpenGLBuffer::VertexBuffer),
+m_ibo(QOpenGLBuffer::IndexBuffer)
+{
+}
+void createShaderProgram()
+{
+if ( !m_pgm.addShaderFromSourceCode( QOpenGLShader::Vertex, vertexShader)) {
+qDebug() << "Error in vertex shader:" << m_pgm.log();
+exit(1);
+}
+if ( !m_pgm.addShaderFromSourceCode( QOpenGLShader::Fragment, fragmentShader)) {
+qDebug() << "Error in fragment shader:" << m_pgm.log();
+exit(1);
+}
+if ( !m_pgm.link() ) {
+qDebug() << "Error linking shader program:" << m_pgm.log();
+exit(1);
+}
+}
+void createGeometry()
+{
+// Initialize and bind the VAO that's going to capture all this vertex state
+m_vao.create();
+m_vao.bind();
+// we need 24 vertices, 24 normals, and 24 colors (6 faces, 4 vertices per face)
+// since we can't share normal data at the corners (each corner gets 3 normals)
+// and since we're not using glVertexAttribDivisor (not available in ES 2.0)
+struct Vertex {
+GLfloat position[3],
+normal  [3],
+color   [3],
+texcoord[2];
+} attribs[24]= {
+// Top face (y = 1.0f)
+{ { 1.0f, 1.0f, -1.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 1.0f, 0.0f}, { 0.0f, 0.0f} },     // Green
+{ {-1.0f, 1.0f, -1.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 1.0f, 0.0f}, { 0.0f, 1.0f} },     // Green
+{ {-1.0f, 1.0f,  1.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 1.0f, 0.0f}, { 1.0f, 1.0f} },     // Green
+{ { 1.0f, 1.0f,  1.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 1.0f, 0.0f}, { 1.0f, 0.0f} },     // Green
+// Bottom face (y = -1.0f)
+{ { 1.0f, -1.0f,  1.0f}, {0.0f, -1.0f, 0.0f}, {1.0f, 0.5f, 0.0f}, { 0.0f, 0.0f} },    // Orange
+{ {-1.0f, -1.0f,  1.0f}, {0.0f, -1.0f, 0.0f}, {1.0f, 0.5f, 0.0f}, { 0.0f, 1.0f} },    // Orange
+{ {-1.0f, -1.0f, -1.0f}, {0.0f, -1.0f, 0.0f}, {1.0f, 0.5f, 0.0f}, { 1.0f, 1.0f} },    // Orange
+{ { 1.0f, -1.0f, -1.0f}, {0.0f, -1.0f, 0.0f}, {1.0f, 0.5f, 0.0f}, { 1.0f, 0.0f} },    // Orange
+// Front face  (z = 1.0f)
+{ { 1.0f,  1.0f, 1.0f}, {0.0f, 0.0f, 1.0f}, {1.0f, 0.0f, 0.0f}, { 0.0f, 0.0f} },     // Red
+{ {-1.0f,  1.0f, 1.0f}, {0.0f, 0.0f, 1.0f}, {1.0f, 0.0f, 0.0f}, { 0.0f, 1.0f} },     // Red
+{ {-1.0f, -1.0f, 1.0f}, {0.0f, 0.0f, 1.0f}, {1.0f, 0.0f, 0.0f}, { 1.0f, 1.0f} },     // Red
+{ { 1.0f, -1.0f, 1.0f}, {0.0f, 0.0f, 1.0f}, {1.0f, 0.0f, 0.0f}, { 1.0f, 0.0f} },     // Red
+// Back face (z = -1.0f)
+{ { 1.0f, -1.0f, -1.0f}, {0.0f, 0.0f, -1.0f}, {1.0f, 1.0f, 0.0f}, { 0.0f, 0.0f} },    // Yellow
+{ {-1.0f, -1.0f, -1.0f}, {0.0f, 0.0f, -1.0f}, {1.0f, 1.0f, 0.0f}, { 0.0f, 1.0f} },    // Yellow
+{ {-1.0f,  1.0f, -1.0f}, {0.0f, 0.0f, -1.0f}, {1.0f, 1.0f, 0.0f}, { 1.0f, 1.0f} },    // Yellow
+{ { 1.0f,  1.0f, -1.0f}, {0.0f, 0.0f, -1.0f}, {1.0f, 1.0f, 0.0f}, { 1.0f, 0.0f} },    // Yellow
+// Left face (x = -1.0f)
+{ {-1.0f,  1.0f,  1.0f}, {-1.0f, 0.0f, 0.0f}, {0.0f, 0.0f, 1.0f}, { 0.0f, 0.0f} },    // Blue
+{ {-1.0f,  1.0f, -1.0f}, {-1.0f, 0.0f, 0.0f}, {0.0f, 0.0f, 1.0f}, { 0.0f, 1.0f} },    // Blue
+{ {-1.0f, -1.0f, -1.0f}, {-1.0f, 0.0f, 0.0f}, {0.0f, 0.0f, 1.0f}, { 1.0f, 1.0f} },    // Blue
+{ {-1.0f, -1.0f,  1.0f}, {-1.0f, 0.0f, 0.0f}, {0.0f, 0.0f, 1.0f}, { 1.0f, 0.0f} },    // Blue
+// Right face (x = 1.0f)
+{ {1.0f,  1.0f, -1.0f}, {1.0f, 0.0f, 0.0f}, {1.0f, 0.0f, 1.0f}, { 0.0f, 0.0f} },     // Magenta
+{ {1.0f,  1.0f,  1.0f}, {1.0f, 0.0f, 0.0f}, {1.0f, 0.0f, 1.0f}, { 0.0f, 1.0f} },     // Magenta
+{ {1.0f, -1.0f,  1.0f}, {1.0f, 0.0f, 0.0f}, {1.0f, 0.0f, 1.0f}, { 1.0f, 1.0f} },     // Magenta
+{ {1.0f, -1.0f, -1.0f}, {1.0f, 0.0f, 0.0f}, {1.0f, 0.0f, 1.0f}, { 1.0f, 0.0f} },     // Magenta
+};
+// Put all the attribute data in a FBO
+m_vbo.create();
+m_vbo.setUsagePattern( QOpenGLBuffer::StaticDraw );
+m_vbo.bind();
+m_vbo.allocate(&attribs, sizeof(attribs));
+// Configure the vertex streams for this attribute data layout
+m_pgm.enableAttributeArray("vertexPosition");
+m_pgm.setAttributeBuffer("vertexPosition", GL_FLOAT, offsetof(Vertex, position), 3, sizeof(Vertex) );
+m_pgm.enableAttributeArray("vertexNormal");
+m_pgm.setAttributeBuffer("vertexNormal", GL_FLOAT, offsetof(Vertex, normal), 3, sizeof(Vertex) );
+m_pgm.enableAttributeArray("vertexColor");
+m_pgm.setAttributeBuffer("vertexColor", GL_FLOAT, offsetof(Vertex, color), 3, sizeof(Vertex) );
+m_pgm.enableAttributeArray("texCoord2d");
+m_pgm.setAttributeBuffer("texCoord2d", GL_FLOAT, offsetof(Vertex, texcoord), 3, sizeof(Vertex) );
+// we need 36 indices (6 faces, 2 triangles per face, 3 vertices per triangle)
+struct {
+GLubyte cube[36];
+} indices;
+m_cnt=0; for (GLsizei i=0, v=0; v<6*4; v+=4)
+{
+// first triangle (ccw winding)
+indices.cube[i++] = v + 0;
+indices.cube[i++] = v + 1;
+indices.cube[i++] = v + 2;
+// second triangle (ccw winding)
+indices.cube[i++] = v + 0;
+indices.cube[i++] = v + 2;
+indices.cube[i++] = v + 3;
+m_cnt = i;
+}
+// Put all the index data in a IBO
+m_ibo.create();
+m_ibo.setUsagePattern( QOpenGLBuffer::StaticDraw );
+m_ibo.bind();
+m_ibo.allocate(&indices, sizeof(indices));
+// Okay, we've finished setting up the vao
+m_vao.release();
+}
+void createTexture(void)
+{
+GLubyte image[16][16][3];
+GLubyte *loc;
+int s, t;
+/* Setup RGB image for the texture. */
+loc = (GLubyte*) image;
+for (t = 0; t < 16; t++) {
+for (s = 0; s < 16; s++) {
+if (circles[t][s] == 'x') {
+/* Nice green. */
+loc[0] = 0x1f;
+loc[1] = 0x8f;
+loc[2] = 0x1f;
+} else {
+/* Light gray. */
+loc[0] = 0xaa;
+loc[1] = 0xaa;
+loc[2] = 0xaa;
+}
+loc += 3;
+}
+}
+glGenTextures  (1, &m_tex);
+glBindTexture  (GL_TEXTURE_2D, m_tex);
+glPixelStorei  (GL_UNPACK_ALIGNMENT, 1);
+glTexImage2D   (GL_TEXTURE_2D, 0, 3, 16, 16, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
+glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+}
+void initializeGL()
+{
+QOpenGLFunctions::initializeOpenGLFunctions();
+createShaderProgram(); m_pgm.bind();
+// Set lighting information
+m_pgm.setUniformValue("lightSource.ambient",  QVector3D( 0.0f, 0.0f, 0.0f )); // opengl fixed-function default
+m_pgm.setUniformValue("lightSource.diffuse",  QVector3D( 1.0f, 1.0f, 1.0f )); // opengl fixed-function default
+m_pgm.setUniformValue("lightSource.specular", QVector3D( 1.0f, 1.0f, 1.0f )); // opengl fixed-function default
+m_pgm.setUniformValue("lightSource.position", QVector3D( 1.0f, 1.0f, 1.0f )); // NOT DEFAULT VALUE
+m_pgm.setUniformValue("lightModel.ambient",   QVector3D( 0.2f, 0.2f, 0.2f )); // opengl fixed-function default
+m_pgm.setUniformValue("material.emission",    QVector3D( 0.0f, 0.0f, 0.0f )); // opengl fixed-function default
+m_pgm.setUniformValue("material.specular",    QVector3D( 1.0f, 1.0f, 1.0f )); // NOT DEFAULT VALUE
+m_pgm.setUniformValue("material.shininess",   10.0f);                         // NOT DEFAULT VALUE
+createGeometry();
+m_view.setToIdentity();
+glEnable(GL_DEPTH_TEST);
+glEnable(GL_TEXTURE_2D);
+glActiveTexture(GL_TEXTURE0);
+m_pgm.setUniformValue("texUnit", 0);
+createTexture();
+glClearColor(.5f,.5f,.5f,1.f);
+}
+void resizeGL(int w, int h)
+{
+glViewport(0, 0, w, h);
+m_projection.setToIdentity();
+if (w <= h)
+m_projection.ortho(-2.f, 2.f, -2.f*h/w, 2.f*h/w, -2.f, 2.f);
+else
+m_projection.ortho(-2.f*w/h, 2.f*w/h, -2.f, 2.f, -2.f, 2.f);
+update();
+}
+void paintGL()
+{
+static unsigned cnt;
+glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+glActiveTexture(GL_TEXTURE0);
+glBindTexture(GL_TEXTURE_2D, m_tex);
+QMatrix4x4 model;
+model.rotate(cnt%360, 1,0,0);
+model.rotate(45, 0,0,1);
+QMatrix4x4 mv = m_view * model;
+m_pgm.bind();
+m_pgm.setUniformValue("modelViewMatrix", mv);
+m_pgm.setUniformValue("normalMatrix", mv.normalMatrix());
+m_pgm.setUniformValue("projectionMatrix", m_projection);
+m_vao.bind();
+glDrawElements(GL_TRIANGLES, m_cnt, GL_UNSIGNED_BYTE, 0);
+update();
+++cnt;
+}
+void keyPressEvent(QKeyEvent * ev)
+{
+switch (ev->key()) {
+case Qt::Key_Escape:
+exit(0);
+break;
+default:
+QOpenGLWindow::keyPressEvent(ev);
+break;
+}
+}
+QMatrix4x4 m_projection, m_view;
+QOpenGLShaderProgram     m_pgm;
+QOpenGLVertexArrayObject m_vao;
+QOpenGLBuffer            m_vbo;
+QOpenGLBuffer            m_ibo;
+GLuint                   m_tex;
+GLsizei                  m_cnt;
+};
+int main(int argc, char *argv[])
+{
+QGuiApplication a(argc,argv);
+Window w;
+w.setWidth(640); w.setHeight(480);
+w.show();
+return a.exec();
+}
diff --git a/hacks/gl/shader.cc b/hacks/gl/shader.cc
new file mode 100644
index 000000000..8d5f5fe70
--- /dev/null
+++ b/hacks/gl/shader.cc
@@ -0,0 +1,50 @@
+#include <wx/wx.h>
+#include <wx/glcanvas.h>
+
+
+
+class GLCanvas
+{
+public:
+	GLCanvas (wxFrame* parent)
+	{
+		_canvas = new wxGLCanvas(parent);
+		Bind(wxEVT_PAINT, bind(&GLCanvas::paint, this);
+	}
+
+	wxWindow* get()
+	{
+		return _canvas;
+	}
+
+	void paint()
+	{
+
+	}
+
+
+private:
+	wxGLCanvas* _canvas;
+};
+
+
+
+class MyApp : public wxApp
+{
+public:
+	bool OnInit()
+	{
+		auto sizer = new wxBoxSizer(wxHORIZONTAL);
+		_frame = new wxFrame(nullptr, wxID_ANY, wxT("Hello world"));
+		_canvas = new GLCanvas(_frame);
+		sizer->Add(_canvas->get(), 1, wxEXPAND);
+		_frame->SetSizerAndFit(sizer);
+		_frame->Show();
+		return true;
+	}
+
+private:
+	wxFrame* _frame;
+	GLCanvas* _canvas;
+};
+