fix glBufferSubData

1 files changed, 141 insertions, 0 deletions

diff --git a/tests/gl_subdata.cpp b/tests/gl_subdata.cpp
new file mode 100644
index 00000000..d159b2b2
--- /dev/null
+++ b/tests/gl_subdata.cpp
@@ -0,0 +1,141 @@
+#define GL_GLEXT_PROTOTYPES
+#define EGL_EGLEXT_PROTOTYPES
+#include <cmath>
+#include <iostream>
+#include <vector>
+extern "C" {
+#include <GL/gl.h>
+#include <GL/glut.h>
+}
+static const char vertex_shader[] =
+        "#ifdef GL_ES\n"
+        "precision highp float;\n"
+        "#endif\n"
+        "attribute float indices;\n"
+        "uniform sampler2D nodeInfo;\n"
+        "varying vec4 color;"
+        "\n"
+        "void main(void)\n"
+        "{\n"
+        "    float s = (indices + 0.5) / 512.; \n"
+        "    vec4  v = texture2D(nodeInfo, vec2( s, 0.5));\n"
+        "    gl_Position = vec4(v.x, v.y, 0.5, 1.);\n"
+        "    gl_PointSize = v.z;\n"
+        "    color = vec4(0.5 + v.w/2., 0.5 + 0.5 * v.w/2., 0.5, 1);\n"
+        "}\n";
+static const char fragment_shader[] =
+        "#ifdef GL_ES\n"
+        "precision highp float;\n"
+        "#endif\n"
+        "\n"
+        "varying vec4 color;\n"
+        "void main(void)\n"
+        "{\n"
+        "  float dst = distance(vec2(0.5, 0.5), gl_PointCoord); \n"
+        "  gl_FragColor = color;\n"
+        "  if ( dst > 0.3) {"
+        "    gl_FragColor = vec4(0., 0., 0.5, 0.2);\n"
+        "}\n"
+        "if ( dst > 0.5) discard;\n"
+        "}";
+struct NodeInfo { //structure that we want to transmit to our shaders
+    float x;
+    float y;
+    float s;
+    float c;
+};
+GLuint nodeTexture; //texture id used to bind
+GLuint nodeSamplerLocation; //shader sampler address
+GLuint indicesAttributeLocation; //shader attribute address
+GLuint indicesVBO; //Vertex Buffer Object Id;
+const int nbNodes = 512;
+NodeInfo data[nbNodes]; //our data that will be transmitted using float texture.
+double alpha = 0; //use to make a simple funny effect;
+static void updateFloatTexture() {
+    int count = 0;
+    for (float x=0; x < nbNodes; ++x ) {
+        data[count].x = 0.2*pow(cos(alpha), 3) + (sin(alpha)*3. + 3.5) * x/nbNodes * cos(alpha + x/nbNodes * 16. * M_PI);
+        data[count].y = 0.2*pow(sin(alpha), 3) + (sin(alpha)*3. + 3.5) * x/nbNodes * sin(alpha + x/nbNodes * 16. * M_PI);
+        data[count].s = (16. + 16. * cos(alpha + x/nbNodes * 32. * M_PI)) + 8.;// * fmod(x/nbNodes + alpha, 1.) + 5.;
+        data[count].c = 0.5 + 0.5 * sin(alpha + x/nbNodes * 32. * M_PI);
+        ++count;
+    }
+    glBindTexture(GL_TEXTURE_2D, nodeTexture);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, nbNodes, 1, 0, GL_RGBA, GL_FLOAT, data);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glBindTexture(GL_TEXTURE_2D, NULL);
+    alpha -= 0.001;
+}
+static void glut_draw_callback(void) {
+    glDisable(GL_CULL_FACE);
+    glDisable(GL_DEPTH_TEST);
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    glClearColor(1., 1., 1., 0.);
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    glActiveTexture(GL_TEXTURE0);
+    updateFloatTexture(); //we change the texture each time to create the effect (it is just for the test)
+    glBindTexture(GL_TEXTURE_2D, nodeTexture);
+    glUniform1i(nodeSamplerLocation, GL_TEXTURE0);
+    glEnableVertexAttribArray(0);
+    glBindBuffer(GL_ARRAY_BUFFER, indicesVBO);
+    glVertexAttribPointer(0, 1, GL_FLOAT, GL_FALSE, 0, NULL);
+    glDrawArrays(GL_POINTS, 0, nbNodes);
+    glutSwapBuffers();
+}
+GLuint createShader(const char source[], int type) {
+    char msg[512];
+    GLuint shader = glCreateShader(type);
+    glShaderSource(shader, 1, (const GLchar**)(&source), NULL);
+    glCompileShader(shader);
+    glGetShaderInfoLog(shader, sizeof msg, NULL, msg);
+    std::cout << "Shader info: " << msg << std::endl;
+    return shader;
+}
+static void gl_init(void) {
+    GLuint program = glCreateProgram();
+    glAttachShader(program, createShader(vertex_shader  , GL_VERTEX_SHADER));
+    glAttachShader(program, createShader(fragment_shader, GL_FRAGMENT_SHADER));
+    glLinkProgram(program);
+    char msg[512];
+    glGetProgramInfoLog(program, sizeof msg, NULL, msg);
+    std::cout << "info: " <<  msg << std::endl;
+    glUseProgram(program);
+    std::vector<float> elements(nbNodes);
+    int count = 0;
+    for (float x=0; x < nbNodes; ++x ) {
+        elements[count] = count;
+        ++count;
+    }
+    /*Create one texture to store all the needed information */
+    glGenTextures(1, &nodeTexture);
+    /* Store the vertices in a vertex buffer object (VBO) */
+    glGenBuffers(1, &indicesVBO);
+    glBindBuffer(GL_ARRAY_BUFFER, indicesVBO);
+    float zeroes[nbNodes];
+    memset(zeroes, 0, sizeof(zeroes));
+    glBufferData(GL_ARRAY_BUFFER, elements.size() * sizeof(float), zeroes, GL_STATIC_DRAW);
+    for (int x = 0; x < nbNodes; x++) {
+      glBufferSubData(GL_ARRAY_BUFFER, x * sizeof(float), elements.size() * sizeof(float), &elements[x]);
+    }
+    /* Get the locations of the uniforms so we can access them */
+    nodeSamplerLocation      = glGetUniformLocation(program, "nodeInfo");
+    glBindAttribLocation(program, 0, "indices");
+    //Enable glPoint size in shader, always enable in Open Gl ES 2.
+    glEnable(GL_VERTEX_PROGRAM_POINT_SIZE);
+    glEnable(GL_POINT_SPRITE);
+}
+int main(int argc, char *argv[]) {
+    glutInit(&argc, argv);
+    glutInitWindowSize(640, 480);
+    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
+    glutCreateWindow("Simple FLOAT Texture Test");
+    /* Set up glut callback functions */
+    glutDisplayFunc(glut_draw_callback      );
+    gl_init();
+    glutMainLoop();
+    return 0;
+}
+
+