opengl_x11

commit c58e453b306bf1c372e59f8f481fc6e1705436bc
parent e0817a497de67eac9cf6389e02e3cc2a0f22c8d4
Author: bsandro <email@bsandro.tech>
Date:   Sun, 23 Nov 2025 22:37:15 +0200

sphere with Mars texture

Diffstat:
A
mars.astc
 | 
0

A
moon.astc
 | 
0

M
sphere.c
 | 
41
++++++++++++++++++++++++++---------------

3 files changed, 26 insertions(+), 15 deletions(-)
diff --git a/mars.astc b/mars.astc
Binary files differ.
diff --git a/moon.astc b/moon.astc
Binary files differ.
diff --git a/sphere.c b/sphere.c
@@ -10,8 +10,9 @@
 #define GL_GLEXT_PROTOTYPES 1
 #include <GL/gl.h>
 #include <GL/glx.h>
-#include <GL/glu.h>
+#include <GL/glu.h> // tesselator
 #include "../cglm/include/cglm/cglm.h"
+#include "astc.h"
 
 #define RANDOM(x) (rand() % (x))
 #define LEN(x) (sizeof(x)/sizeof(x[0]))
@@ -27,8 +28,8 @@ x;                                                                              
 }
 
 // I can push that to the local variables but want to keep the array on stack for now.
-#define STACKS 24
-#define SECTORS 24
+#define STACKS 64
+#define SECTORS 64
 
 static const double current_ts() {
     struct timespec ts;
@@ -43,20 +44,25 @@ static const GLchar *vertexSrc = R"(
 #version 420
 layout(location=0) in vec3 position;
 layout(location=1) in vec2 aTexCoord;
+out vec2 texCoord;
 uniform mat4 model;
 uniform mat4 view;
 uniform mat4 projection;
 void main() {
     gl_Position = projection * view * model * vec4(position, 1.0);
+    texCoord = aTexCoord;
 }
 )";
 
 static const GLchar *fragmentSrc = R"(
 #version 420
 uniform double iTime;
+uniform sampler2D ourTex;
 out vec4 outColor;
+in vec2 texCoord;
 void main() {
-    outColor = vec4(0.1f, 0.5f, 0.2f, 0.0f);
+    //outColor = vec4(0.1f, 0.5f, 0.2f, 0.0f);
+    outColor = texture(ourTex, texCoord);
 }
 )";
 
@@ -116,7 +122,6 @@ void generateSphere(float radius, int stacks, int sectors, GLfloat outVertices[]
     float stackStep = M_PI/stacks;
     float sectorStep = (2.f*M_PI)/sectors;
     int offset = 0;
-    // deliberate <=
     for (int i=0;i<=stacks;++i) {
         float stackAngle = M_PI_2 - (float)i*stackStep;
         float xy = radius*cosf(stackAngle);
@@ -125,17 +130,19 @@ void generateSphere(float radius, int stacks, int sectors, GLfloat outVertices[]
             float sectorAngle = (float)j*sectorStep;
             float x = xy*cosf(sectorAngle);
             float y = xy*sinf(sectorAngle);
-            assert(offset < (stacks+1)*(sectors+1)*3 - 2);
+            float u = (float)j / sectors;
+            float v = (float)i / stacks;
             outVertices[offset++] = x;
             outVertices[offset++] = y;
             outVertices[offset++] = z;
+            outVertices[offset++] = u;
+            outVertices[offset++] = v;
         }
     }
-    printf("offset: %d\n", offset);
 }
 
 void generateElements(int stacks, int sectors, GLuint outElements[]) {
-    GLuint offset = 0;
+    uint32_t offset = 0;
     for (int i=0;i<stacks;++i) {
         int k1 = i*(sectors+1);
         int k2 = k1+sectors+1;
@@ -152,8 +159,7 @@ void generateElements(int stacks, int sectors, GLuint outElements[]) {
             }
         }
     }
-    printf("elements: %lu, total: %lu\n", offset, (stacks-1)*sectors*6);
-    assert(offset <= (stacks-1)*sectors*6);
+    printf("elements offset: %lu\n", offset);
 }
 
 int main(int argc, char *argv[]) {
@@ -192,9 +198,9 @@ int main(int argc, char *argv[]) {
     glBindVertexArray(vao);
 
     const float radius = .9f;
-    // x,y,z
-    GLfloat vertices[(STACKS+1)*(SECTORS+1)*3];
-    GLuint elements[(STACKS-1)*SECTORS*6];
+    // x,y,z,u,v
+    GLfloat vertices[(STACKS+1)*(SECTORS+1)*5];
+    GLuint elements[(STACKS-1)*(SECTORS)*6];
     generateSphere(radius, STACKS, SECTORS, vertices);
     generateElements(STACKS, SECTORS, elements);
 
@@ -222,9 +228,14 @@ int main(int argc, char *argv[]) {
     glGetProgramiv(shaderPrg, GL_LINK_STATUS, &prgStatus);
     printf("shader link status: %s\n", prgStatus == GL_TRUE ? "ok" : "error");
 
+    GLuint tex = mkTextureAstc("mars.astc");
+
     GLint position = glGetAttribLocation(shaderPrg, "position");
-    glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 3*sizeof(GLfloat), (void *)0);
+    glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 5*sizeof(GLfloat), (void *)0);
     glEnableVertexAttribArray(position);
+    GLint aTexCoord = glGetAttribLocation(shaderPrg, "aTexCoord");
+    glVertexAttribPointer(aTexCoord, 2, GL_FLOAT, GL_FALSE, 5*sizeof(GLfloat), (void *)(3*sizeof(GLfloat)));
+    glEnableVertexAttribArray(aTexCoord);
 
     mat4 model;
     glm_mat4_identity(model);
@@ -288,7 +299,7 @@ int main(int argc, char *argv[]) {
         // ultra useful debug
         glLineWidth(1.0f);
         glPointSize(4.0f);
-        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+        //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 
         for (int i=0; i<LEN(positions); ++i) {
             mat4 model;