--- /dev/null
+/**
+ * Vertex shader texture sampling test.
+ * Brian Paul
+ * 2 Dec 2008
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/gl.h>
+#include <GL/glut.h>
+#include <GL/glext.h>
+#include "extfuncs.h"
+#include "shaderutil.h"
+
+
+static const char *VertShaderText =
+ "uniform sampler2D tex1; \n"
+ "void main() \n"
+ "{ \n"
+ " vec4 pos = gl_Vertex; \n"
+ " pos.z = texture2D(tex1, gl_MultiTexCoord0.xy).x - 0.5; \n"
+ " gl_Position = gl_ModelViewProjectionMatrix * pos; \n"
+ " gl_FrontColor = pos; \n"
+ "} \n";
+
+static const char *FragShaderText =
+ "void main() \n"
+ "{ \n"
+ " gl_FragColor = gl_Color; \n"
+ "} \n";
+
+
+static GLuint fragShader;
+static GLuint vertShader;
+static GLuint program;
+
+static GLint win = 0;
+static GLboolean Anim = GL_TRUE;
+static GLboolean WireFrame = GL_TRUE;
+static GLfloat xRot = -70.0f, yRot = 0.0f, zRot = 0.0f;
+
+
+/* value[0] = tex unit */
+static struct uniform_info Uniforms[] = {
+ { "tex1", 1, GL_INT, { 0, 0, 0, 0 }, -1 },
+ END_OF_UNIFORMS
+};
+
+
+
+static void
+Idle(void)
+{
+ zRot = 90 + glutGet(GLUT_ELAPSED_TIME) * 0.05;
+ glutPostRedisplay();
+}
+
+
+static void
+DrawMesh(void)
+{
+ GLfloat xmin = -2.0, xmax = 2.0;
+ GLfloat ymin = -2.0, ymax = 2.0;
+ GLuint xdivs = 20, ydivs = 20;
+ GLfloat dx = (xmax - xmin) / xdivs;
+ GLfloat dy = (ymax - ymin) / ydivs;
+ GLfloat ds = 1.0 / xdivs, dt = 1.0 / ydivs;
+ GLfloat x, y, s, t;
+ GLuint i, j;
+
+ y = ymin;
+ t = 0.0;
+ for (i = 0; i < ydivs; i++) {
+ x = xmin;
+ s = 0.0;
+ glBegin(GL_QUAD_STRIP);
+ for (j = 0; j < xdivs; j++) {
+ glTexCoord2f(s, t);
+ glVertex2f(x, y);
+ glTexCoord2f(s, t + dt);
+ glVertex2f(x, y + dy);
+ x += dx;
+ s += ds;
+ }
+ glEnd();
+ y += dy;
+ t += dt;
+ }
+}
+
+
+static void
+Redisplay(void)
+{
+ if (WireFrame)
+ glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+ else
+ glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ glPushMatrix();
+ glRotatef(xRot, 1.0f, 0.0f, 0.0f);
+ glRotatef(yRot, 0.0f, 1.0f, 0.0f);
+ glRotatef(zRot, 0.0f, 0.0f, 1.0f);
+
+ glPushMatrix();
+ DrawMesh();
+ glPopMatrix();
+
+ glPopMatrix();
+
+ glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+ glViewport(0, 0, width, height);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+ glTranslatef(0.0f, 0.0f, -15.0f);
+}
+
+
+static void
+CleanUp(void)
+{
+ glDeleteShader_func(fragShader);
+ glDeleteShader_func(vertShader);
+ glDeleteProgram_func(program);
+ glutDestroyWindow(win);
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+ const GLfloat step = 2.0;
+ (void) x;
+ (void) y;
+
+ switch(key) {
+ case 'a':
+ Anim = !Anim;
+ if (Anim)
+ glutIdleFunc(Idle);
+ else
+ glutIdleFunc(NULL);
+ break;
+ case 'w':
+ WireFrame = !WireFrame;
+ break;
+ case 'z':
+ zRot += step;
+ break;
+ case 'Z':
+ zRot -= step;
+ break;
+ case 27:
+ CleanUp();
+ exit(0);
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+static void
+SpecialKey(int key, int x, int y)
+{
+ const GLfloat step = 2.0;
+
+ (void) x;
+ (void) y;
+
+ switch(key) {
+ case GLUT_KEY_UP:
+ xRot += step;
+ break;
+ case GLUT_KEY_DOWN:
+ xRot -= step;
+ break;
+ case GLUT_KEY_LEFT:
+ yRot -= step;
+ break;
+ case GLUT_KEY_RIGHT:
+ yRot += step;
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+static void
+MakeTexture(void)
+{
+ const GLuint texWidth = 64, texHeight = 64;
+ GLfloat texImage[64][64];
+ GLuint i, j;
+
+ /* texture is basically z = f(x, y) */
+ for (i = 0; i < texHeight; i++) {
+ GLfloat y = 2.0 * (i / (float) (texHeight - 1)) - 1.0;
+ for (j = 0; j < texWidth; j++) {
+ GLfloat x = 2.0 * (j / (float) (texWidth - 1)) - 1.0;
+ GLfloat z = 0.5 + 0.5 * (sin(4.0 * x) * sin(4.0 * y));
+ texImage[i][j] = z;
+ }
+ }
+
+ glActiveTexture(GL_TEXTURE0);
+ glBindTexture(GL_TEXTURE_2D, 42);
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_INTENSITY, texWidth, texHeight, 0,
+ GL_LUMINANCE, GL_FLOAT, texImage);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+}
+
+
+static void
+Init(void)
+{
+ GLint m;
+
+ glGetIntegerv(GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS_ARB, &m);
+ if (m < 1) {
+ printf("Error: no vertex shader texture units supported.\n");
+ exit(1);
+ }
+
+ if (!ShadersSupported())
+ exit(1);
+
+ GetExtensionFuncs();
+
+ vertShader = CompileShaderText(GL_VERTEX_SHADER, VertShaderText);
+ fragShader = CompileShaderText(GL_FRAGMENT_SHADER, FragShaderText);
+ program = LinkShaders(vertShader, fragShader);
+
+ glUseProgram_func(program);
+
+ assert(glGetError() == 0);
+
+ MakeTexture();
+
+ glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
+
+ glEnable(GL_DEPTH_TEST);
+
+ glColor3f(1, 1, 1);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+ glutInit(&argc, argv);
+ glutInitWindowSize(500, 500);
+ glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
+ win = glutCreateWindow(argv[0]);
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutSpecialFunc(SpecialKey);
+ glutDisplayFunc(Redisplay);
+ Init();
+ if (Anim)
+ glutIdleFunc(Idle);
+ glutMainLoop();
+ return 0;
+}
+
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