The identity matrix, in terms of the projection and modelview matrices, essentially resets the matrix back to its default state. As you hopefully know, glTranslate and glRotate are always relative to the matrix’s current state. So for instance, if you call glTranslate, you are translating from the matrix’s current ‘position’, not from the origin. But … Read more
You can use glRotate to rotate around an axis, by an amount which is given by the relative mouse movement (pygame.mouse.get_rel()): mouseMove = pygame.mouse.get_rel() glRotatef(mouseMove[0]*0.1, 0.0, 1.0, 0.0) But that won’t satisfy you, because the solution won’t work any more, if the mouse leaves the window. You’ve to center the mouse in the middle of … Read more
GL_UNPACK_ALIGNMENT specifies the alignment requirements for the start of each pixel row in memory. By default GL_UNPACK_ALIGNMENT is set to 4. This means each row of the texture is supposed to have a length of 4*N bytes. You specify a 2*2 texture with the data: 255, 0, 0, 255, 0, 0, 255, 0, 0, 255, … Read more
This error is because Big Sur no longer has the OpenGL library nor other system libraries in standard locations in the file system and instead uses a cache. PyOpenGL uses ctypes to try to locate the OpenGL library and it fails to find it. Fixing ctypes in Python so that it will find the library … Read more
SDL_CreateTexture() w/SDL_TEXTUREACCESS_STREAMING + SDL_UpdateTexture() seems to work well enough with the right pixel format. On my system using the default renderer: Renderer name: direct3d Texture formats: SDL_PIXELFORMAT_ARGB8888 SDL_PIXELFORMAT_YV12 SDL_PIXELFORMAT_IYUV (though the opengl info is the same:) Renderer name: opengl Texture formats: SDL_PIXELFORMAT_ARGB8888 SDL_PIXELFORMAT_YV12 SDL_PIXELFORMAT_IYUV SDL_PIXELFORMAT_ARGB8888 gives me ~1ms/frame: // g++ main.cpp `pkg-config –cflags –libs sdl2` … Read more
First of all, I’d avoid using glut — it’s buggy, hasn’t been updated in roughly a decade, and its design doesn’t really fit very well with what most people want today (e.g., though you can use it for animations, it’s really intended primarily to produce a static display). I pointed out a number of alternatives … Read more
Look my simple c implementation function to load texture. GLuint LoadTexture( const char * filename ) { GLuint texture; int width, height; unsigned char * data; FILE * file; file = fopen( filename, “rb” ); if ( file == NULL ) return 0; width = 1024; height = 512; data = (unsigned char *)malloc( width … Read more
GL_POLYGON is only for convex polygons: GL_POLYGON: Draws a single, convex polygon. Vertices 1 through N define this polygon. For concave polygons you have at least two options: Triangulate the polygon and use GL_TRIANGLES. Use the stencil buffer trick.
For each plane of the tetrahedron, check if the point is on the same side as the remaining vertex: bool SameSide(v1, v2, v3, v4, p) { normal := cross(v2 – v1, v3 – v1) dotV4 := dot(normal, v4 – v1) dotP := dot(normal, p – v1) return Math.Sign(dotV4) == Math.Sign(dotP); } And you need to … Read more
Simple cylinder wrap with Canvas 2D Very simple example using sin and cos to create the curved map. The images is cut into strips approx 1 pixel wide then rendered as half a squashed circle. As perspective is a linear effect related to distance I also add a small amount of perspective by scaling up … Read more