v4l and opengl revamp

Author: cirosantilli

opencl/benchmarks.md

@@ -2,3 +2,4 @@
 
 - <https://compubench.com> Also from Kishonti who makes GFXBench.
 - <http://geekbench.com/> Proprietary by <http://www.primatelabs.com/>, looks like similar business model to Kishonti (license source).
+- <https://github.com/vetter/shoc> BSD

opencl/introduction.md

@@ -23,7 +23,11 @@ OpenCL, like any other language has versions. As of 2013 the latest version is O
 
 ## OpenCL and OpenGL integration
 
-- <http://stackoverflow.com/questions/4005935/mix-opencl-with-opengl>
 - <http://enja.org/2010/08/27/adventures-in-opencl-part-2-particles-with-opengl/>
+- <http://stackoverflow.com/questions/17899514/opencl-opengl-interop-performance>
+- <http://stackoverflow.com/questions/4005935/mix-opencl-with-opengl>
+- <http://stackoverflow.com/questions/7907510/opengl-vs-opencl-which-to-choose-and-why>
+- <http://stackoverflow.com/questions/8824269/gl-cl-interoperability-shared-texture>
+- <https://github.com/9prady9/CLGLInterop>
 
-Also see compute shaders for OpenGL, they seem to integrate better.
+Also see compute shaders for OpenGL 4.X, they seem to integrate better.

opengl/README.md

@@ -49,8 +49,10 @@
         1.  [IBO](glfw_ibo.c)
         1.  [transform](glfw_transform.c)
         1.  [gl_FragCoord](glfw_gl_frag_coord.c)
-        1.  [heatmap](glfw_heatmap.c)
         1.  [Texture](glfw_texture.c)
+            1.  [Image processing](glfw_image_processing.c.off)
+            1.  [Recursive](glfw_recursive.c.off)
+        1.  [heatmap](glfw_heatmap.c)
         1.  Naughty
             1.  [Infinite loop shader](glfw_infinite_loop_shader.c.off)
             1.  [Memory overflow shader](glfw_memory_overflow_shader.c.off)

opengl/TODO.md

@@ -82,7 +82,6 @@
 -   HUD, billboards, draw pixel on screen:
     - people suggest: glOrtho + disable depth tests
     - could think about a transparent texture right on top of the camera
-    - http://stackoverflow.com/questions/10040961/opengl-pixel-perfect-2d-drawing
     - http://stackoverflow.com/questions/4282036/rendering-2d-sprites-in-a-3d-world/36568461#36568461
     - http://stackoverflow.com/questions/6151135/in-opengl-can-i-draw-a-pixel-that-exactly-at-the-coordinates-5-5
     - http://gamedev.stackexchange.com/questions/5959/rendering-2d-sprites-into-a-3d-world/119739#119739
@@ -91,6 +90,11 @@
     - http://stackoverflow.com/questions/18362058/opengl-draw-pixels-directly
     - http://stackoverflow.com/questions/6644248/how-to-draw-opencl-calculated-pixels-to-the-screen-with-opengl
     - also useful to render "particles": things that are so far / so small that a billboards approximate well enough with less overhead
+-   2D acceleration (translation, rotation, alpha blending, z-order) and pixel perfectness:
+    - http://stackoverflow.com/questions/10040961/opengl-pixel-perfect-2d-drawing
+    - http://stackoverflow.com/questions/3919307/is-there-a-2d-graphics-api-with-both-pixel-perfect-drawing-and-2d-hardware-accel
+    - <http://stackoverflow.com/questions/7922526/opengl-deterministic-rendering-between-gpu-vendor>
+    - <http://stackoverflow.com/questions/671395/a-simple-2d-cross-platform-graphics-library-for-c-or-c/718384#718384>
 -   text, fonts
     - glut does it
     - non trivial: most fonts are specified in vector formats with Bezier curves, and OpenGL does not have any primitives for that

opengl/benchmarks.md

@@ -12,4 +12,4 @@ Free:
 
 Non free:
 
-- GFXBench: <https://gfxbench.com/result.jsp>
+- GFXBench: <https://gfxbench.com/result.jsp> By a company called Koshonti. You can run it for free on most devices, but they license the source (and TODO more complete versions?) to companies as a business model.

opengl/bibliography.md

@@ -36,6 +36,7 @@ Tutorials with runnable version tracked code:
 
 Samples without tutorial:
 
+- <https://github.com/openglsuperbible/sb7code> MIT licensed samples from OpenGL superbible book by AMD employee. Very good.
 - <https://github.com/g-truc/ogl-samples> Many precise examples of specific OpenGL API features, organized by API version.
 
 Tutorials with runnable code that is not version tracked:
@@ -62,7 +63,6 @@ Demos:
 
 - <https://github.com/prideout/recipes>
 - <https://www.youtube.com/watch?v=H-3yPXXZUC8>
-- <https://github.com/premsasidharan/gpu_img_proc/tree/master/test/edge_camera> <https://www.youtube.com/watch?v=fJtOdJ9MHsA> GLSL Linux camera real time edge detection shown on screen. Getting started: <https://github.com/premsasidharan/gpu_img_proc/issues/1#issuecomment-257504913>
 
 Unevaluated:
 

opengl/glfw_gl_frag_coord.c

@@ -34,48 +34,50 @@ static const GLfloat vertices[] = {
 
 int main(void) {
     GLFWwindow *window;
-    GLint attribute_coord2d, program;
-    GLuint vbo;
+    GLint attribute_coord2d;
+    GLuint program, vbo;
     const char *attribute_name = "coord2d";
 
+    /* Window system. */
     glfwInit();
+    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
     window = glfwCreateWindow(WIDTH, HEIGHT, __FILE__, NULL, NULL);
     glfwMakeContextCurrent(window);
     glewInit();
 
+    /* Shader setup. */
     program = common_get_shader_program(vertex_shader_source, fragment_shader_source);
     attribute_coord2d = glGetAttribLocation(program, attribute_name);
-    if (attribute_coord2d == -1) {
-        fprintf(stderr, "error: attribute_coord2d: %s\n", attribute_name);
-        return EXIT_FAILURE;
-    }
-
-    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
-    glUseProgram(program);
-    glViewport(0, 0, WIDTH, HEIGHT);
 
+    /* vbo */
     glGenBuffers(1, &vbo);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
+    /* Draw. */
+    glViewport(0, 0, WIDTH, HEIGHT);
+    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT);
+    glUseProgram(program);
+    glEnableVertexAttribArray(attribute_coord2d);
+    glVertexAttribPointer(
+        attribute_coord2d,
+        2,
+        GL_FLOAT,
+        GL_FALSE,
+        0,
+        0
+    );
+    glDrawArrays(GL_TRIANGLES, 0, 6);
+    glDisableVertexAttribArray(attribute_coord2d);
+    glfwSwapBuffers(window);
+
+    /* Main loop. */
     while (!glfwWindowShouldClose(window)) {
         glfwPollEvents();
-        glClear(GL_COLOR_BUFFER_BIT);
-        glEnableVertexAttribArray(attribute_coord2d);
-        glVertexAttribPointer(
-            attribute_coord2d,
-            2,
-            GL_FLOAT,
-            GL_FALSE,
-            0,
-            0
-        );
-        glDrawArrays(GL_TRIANGLES, 0, 6);
-        glDisableVertexAttribArray(attribute_coord2d);
-        glfwSwapBuffers(window);
-        glfwSwapBuffers(window);
     }
 
+    /* Cleanup. */
     glDeleteBuffers(1, &vbo);
     glDeleteProgram(program);
     glfwTerminate();

opengl/glfw_heatmap.c

@@ -12,16 +12,12 @@ static const GLchar* fragment_shader_source =
     "#version 120\n"
     "uniform float pi2;\n"
     "uniform float time;\n"
-    "uniform float width;\n"
-    "uniform float height;\n"
-    "uniform float periods_x;\n"
-    "uniform float periods_y;\n"
+    "uniform vec2 win_dim;\n"
+    "uniform vec2 periods;\n"
     "void main(void) {\n"
-    "    float center_x = width / 2.0;"
-    "    float center_y = height / 2.0;"
-    "    float x = (gl_FragCoord.x - center_x) * periods_x / width;"
-    "    float y = (gl_FragCoord.y - center_y) * periods_y / height;"
-    "    gl_FragColor[0] = 0.5 * (1.0 + (sin((pi2 * (sqrt(x*x + y*y) + time)))));\n"
+    "    vec2 center = win_dim / 2.0;"
+    "    vec2 xy = (gl_FragCoord.xy - center) * periods / win_dim;"
+    "    gl_FragColor[0] = 0.5 * (1.0 + (sin((pi2 * (length(xy) + time)))));\n"
     "    gl_FragColor[1] = 0.0;\n"
     "    gl_FragColor[2] = 0.0;\n"
     "}\n";
@@ -41,15 +37,12 @@ int main(void) {
     GLint
         attribute_coord2d,
         ibo_size,
-        width_location,
-        height_location,
-        time_location,
-        periods_x_location,
-        periods_y_location,
+        periods_location,
         pi2_location,
-        program
+        time_location,
+        win_dim_location
     ;
-    GLuint ibo, vbo;
+    GLuint ibo, program, vbo;
     const char *attribute_name = "coord2d";
     const float
         periods_x = 5.0,
@@ -66,12 +59,10 @@ int main(void) {
     /* Shader setup. */
     program = common_get_shader_program(vertex_shader_source, fragment_shader_source);
     attribute_coord2d = glGetAttribLocation(program, attribute_name);
-    height_location = glGetUniformLocation(program, "height");
-    periods_x_location = glGetUniformLocation(program, "periods_x");
-    periods_y_location = glGetUniformLocation(program, "periods_y");
+    periods_location = glGetUniformLocation(program, "periods");
     pi2_location = glGetUniformLocation(program, "pi2");
     time_location = glGetUniformLocation(program, "time");
-    width_location = glGetUniformLocation(program, "width");
+    win_dim_location = glGetUniformLocation(program, "win_dim");
 
     /* Global settings. */
     glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
@@ -82,6 +73,15 @@ int main(void) {
     glGenBuffers(1, &vbo);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+    glVertexAttribPointer(
+        attribute_coord2d,
+        2,
+        GL_FLOAT,
+        GL_FALSE,
+        0,
+        0
+    );
+    glEnableVertexAttribArray(attribute_coord2d);
 
     /* ibo */
     glGenBuffers(1, &ibo);
@@ -91,35 +91,22 @@ int main(void) {
 
     /* Uniforms. */
     glUniform1f(pi2_location, pi2);
-    glUniform1f(width_location, WIDTH);
-    glUniform1f(height_location, HEIGHT);
-    glUniform1f(periods_x_location, periods_x);
-    glUniform1f(periods_y_location, periods_y);
+    glUniform2f(win_dim_location, WIDTH, HEIGHT);
+    glUniform2f(periods_location, periods_x, periods_y);
 
     /* Main loop. */
     common_fps_init();
     while (!glfwWindowShouldClose(window)) {
         glfwPollEvents();
         glClear(GL_COLOR_BUFFER_BIT);
-        glEnableVertexAttribArray(attribute_coord2d);
-        glBindBuffer(GL_ARRAY_BUFFER, vbo);
-        glVertexAttribPointer(
-            attribute_coord2d,
-            2,
-            GL_FLOAT,
-            GL_FALSE,
-            0,
-            0
-        );
-        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
         glUniform1f(time_location, glfwGetTime());
         glDrawElements(GL_TRIANGLES, ibo_size / sizeof(indexes[0]), GL_UNSIGNED_INT, 0);
-        glDisableVertexAttribArray(attribute_coord2d);
         glfwSwapBuffers(window);
         common_fps_print();
     }
 
     /* Cleanup. */
+    glDisableVertexAttribArray(attribute_coord2d);
     glDeleteBuffers(1, &ibo);
     glDeleteBuffers(1, &vbo);
     glDeleteProgram(program);

opengl/glfw_image_process.c.off

@@ -0,0 +1,14 @@
+/*
+The principle is that fragment shaders can access any byte of a texture,
+and so do operations over multiple pixels.
+
+-   <http://stackoverflow.com/questions/13693946/image-processing-with-glsl-shaders>
+-   <https://github.com/premsasidharan/gpu_img_proc/tree/master/test/edge_camera>
+    <https://www.youtube.com/watch?v=fJtOdJ9MHsA> GLSL Linux camera real time edge detection shown on screen. Getting started: <https://github.com/premsasidharan/gpu_img_proc/issues/1#issuecomment-257504913>
+
+Post processing is equivalent to image processing (unless there is some
+magic Krhonos way to bypass the CPU camera image copy to texture):
+
+-   <https://en.wikibooks.org/wiki/OpenGL_Programming/Post-Processing>
+-   r3dux tori demo <https://www.youtube.com/watch?v=9nDxIbj3mPU>
+*/

opengl/glfw_recursive.c.off

@@ -0,0 +1,8 @@
+/*
+Recursive calculations where the input to the next frame is the previous frame.
+
+Conway's game of life is a popular example:
+
+- http://nullprogram.com/blog/2014/06/10/
+- http://gamedev.stackexchange.com/questions/87213/how-to-read-neighbor-pixels-in-glsl
+*/