Mesa (master): demos: new glsl/array.c demo
Brian Paul
brianp at kemper.freedesktop.org
Fri Apr 17 22:26:26 UTC 2009
Module: Mesa
Branch: master
Commit: 538a82388293ca1b14e6eb8b26179d1f42627210
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=538a82388293ca1b14e6eb8b26179d1f42627210
Author: Brian Paul <brianp at vmware.com>
Date: Fri Apr 17 16:23:33 2009 -0600
demos: new glsl/array.c demo
Test variable indexing into a uniform array in a vertex shader.
---
progs/glsl/Makefile | 8 ++
progs/glsl/array.c | 261 +++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 269 insertions(+), 0 deletions(-)
diff --git a/progs/glsl/Makefile b/progs/glsl/Makefile
index 0f1a299..5fb95c4 100644
--- a/progs/glsl/Makefile
+++ b/progs/glsl/Makefile
@@ -10,6 +10,7 @@ LIB_DEP = $(TOP)/$(LIB_DIR)/$(GL_LIB_NAME) $(TOP)/$(LIB_DIR)/$(GLU_LIB_NAME) $(T
LIBS = -L$(TOP)/$(LIB_DIR) -l$(GLUT_LIB) -l$(GLU_LIB) -l$(GL_LIB) $(APP_LIB_DEPS)
PROGS = \
+ array \
bitmap \
brick \
bump \
@@ -80,6 +81,13 @@ shaderutil.o: shaderutil.c shaderutil.h
+array.o: array.c extfuncs.h shaderutil.h
+ $(APP_CC) -c -I$(INCDIR) $(CFLAGS) array.c
+
+array: array.o shaderutil.o
+ $(APP_CC) -I$(INCDIR) $(CFLAGS) $(LDFLAGS) array.o shaderutil.o $(LIBS) -o $@
+
+
bitmap.o: bitmap.c extfuncs.h shaderutil.h
$(APP_CC) -c -I$(INCDIR) $(CFLAGS) bitmap.c
diff --git a/progs/glsl/array.c b/progs/glsl/array.c
new file mode 100644
index 0000000..46ef804
--- /dev/null
+++ b/progs/glsl/array.c
@@ -0,0 +1,261 @@
+/**
+ * Test variable array indexing in a vertex shader.
+ * Brian Paul
+ * 17 April 2009
+ */
+
+#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"
+
+
+/**
+ * The vertex position.z is used as a (variable) index into an
+ * array which returns a new Z value.
+ */
+static const char *VertShaderText =
+ "uniform sampler2D tex1; \n"
+ "uniform float HeightArray[20]; \n"
+ "void main() \n"
+ "{ \n"
+ " vec4 pos = gl_Vertex; \n"
+ " int i = int(pos.z * 9.5); \n"
+ " pos.z = HeightArray[i]; \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;
+
+
+static void
+Idle(void)
+{
+ zRot = 90 + glutGet(GLUT_ELAPSED_TIME) * 0.05;
+ glutPostRedisplay();
+}
+
+
+/** z=f(x,y) */
+static float
+fz(float x, float y)
+{
+ return fabs(cos(1.5*x) + cos(1.5*y));
+}
+
+
+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++) {
+ float z0 = fz(x, y), z1 = fz(x, y + dy);
+
+ glTexCoord2f(s, t);
+ glVertex3f(x, y, z0);
+
+ glTexCoord2f(s, t + dt);
+ glVertex3f(x, y + dy, z1);
+ x += dx;
+ s += ds;
+ }
+ glEnd();
+ y += dy;
+ t += dt;
+ }
+}
+
+
+static void
+Redisplay(void)
+{
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ if (WireFrame)
+ glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+ else
+ glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+
+ 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();
+
+ glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+
+ 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
+Init(void)
+{
+ GLfloat HeightArray[20];
+ GLint u, i;
+
+ if (!ShadersSupported())
+ exit(1);
+
+ GetExtensionFuncs();
+
+ vertShader = CompileShaderText(GL_VERTEX_SHADER, VertShaderText);
+ fragShader = CompileShaderText(GL_FRAGMENT_SHADER, FragShaderText);
+ program = LinkShaders(vertShader, fragShader);
+
+ glUseProgram_func(program);
+
+ /* Setup the HeightArray[] uniform */
+ for (i = 0; i < 20; i++)
+ HeightArray[i] = i / 20.0;
+ u = glGetUniformLocation_func(program, "HeightArray");
+ glUniform1fv_func(u, 20, HeightArray);
+
+ assert(glGetError() == 0);
+
+ 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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