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I went ahead and attached the basic test program I created to showcase the issue.

TestApp.c (text/plain), 4.55 KB, created by akakubiyaro on 2018-01-31 21:01:14 UTC

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Description:

Filename:

MIME Type:

Creator: akakubiyaro

Created: 2018-01-31 21:01:14 UTC

Size: 4.55 KB

patch

obsolete

>
>#define TEXTURE_SIZE 256
>#define TILE_COLS 64
>#define TILE_ROWS 64
>#define CHECKER_SIZE 32
>#define SCROLL_SPEED 4
>#define USE_VSYNC 1
>
>#include <SDL2/SDL.h>
>#include <OpenGL/gl.h>
>#include <OpenGL/glu.h>
>#include <OpenGL/glext.h>
>
>#include <stdio.h>
>#include <stdlib.h>
>#include <stdbool.h>
>
>struct Rectf { float x, y, w, h; };
>
>static SDL_Window *RenderWindow = NULL;
>static SDL_GLContext RenderContext = NULL;
>
>static double ViewportW;
>static double ViewportH;
>static double HalfViewportW;
>static double HalfViewportH;
>static double ViewportScaleW;
>static double ViewportScaleH;
>
>static GLuint TestTextureId;
>
>static float WorldX, WorldY;
>
>static inline void InitSDL()
>{
>	SDL_Init(SDL_INIT_VIDEO);
>	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
>	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);
>	RenderWindow = SDL_CreateWindow (
>		"TestApp",
>		SDL_WINDOWPOS_CENTERED,
>		SDL_WINDOWPOS_CENTERED,
>		0,
>		0,
>		SDL_WINDOW_OPENGL | SDL_WINDOW_FULLSCREEN_DESKTOP
>	);
>	RenderContext = SDL_GL_CreateContext(RenderWindow);
>	SDL_GL_SetSwapInterval(USE_VSYNC);
>}
>
>static inline void InitOpenGL()
>{
>	int w, h;
>	SDL_GetWindowSize(RenderWindow, &w, &h);
>	glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
>	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
>	glEnable(GL_BLEND);
>	glDisable(GL_DEPTH_TEST);
>	glEnable(GL_CULL_FACE);
>	glFrontFace(GL_CCW);
>	ViewportW = (double)w;
>	ViewportH = (double)h;
>	HalfViewportW = ViewportW * 0.5;
>	HalfViewportH = ViewportH * 0.5;
>	ViewportScaleW = 2.0/ViewportW;
>	ViewportScaleH = 2.0/ViewportH;
>	glViewport(0, 0, ViewportW, ViewportH);
>}
>
>static inline void InitTestTexture()
>{
>	struct Pixel
>	{
>		uint8_t r, g, b, a;
>	};
>	int w = TEXTURE_SIZE, h = TEXTURE_SIZE, n = 4;
>	int total = w * h;
>	struct Pixel *pixels = malloc(sizeof(struct Pixel) * total);
>	int xcount = 0;
>	int ycount = 0;
>	bool red = true;
>	for(int i = 0; i < total; i++)
>	{
>		if(ycount >= CHECKER_SIZE)
>		{
>			red = !red;
>			ycount = 0;
>		}
>		if(xcount >= CHECKER_SIZE)
>		{
>			red = !red;
>			xcount = 0;
>		}
>		if(red)
>		{
>			pixels[i].r = 128;
>			pixels[i].g = 0;
>			pixels[i].b = 128;
>			pixels[i].a = 255;
>		}
>		else
>		{
>			pixels[i].r = 255;
>			pixels[i].g = 255;
>			pixels[i].b = 255;
>			pixels[i].a = 255;
>		}
>		xcount += 1;
>		if(i != 0 && i % TEXTURE_SIZE == 0)
>		{
>			ycount++;
>		}
>	}
>	glEnable(GL_TEXTURE_2D);
>	glGenTextures(1, &TestTextureId);
>	glBindTexture(GL_TEXTURE_2D, TestTextureId);
>	glTexImage2D(GL_TEXTURE_2D, 0, n, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
>	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
>    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
>}
>
>static inline void HandleSDLEvents()
>{
>	SDL_Event event;
>	while(SDL_PollEvent(&event))
>	{
>		switch(event.type)
>		{
>			case SDL_QUIT:
>				exit(0);
>				break;
>			case SDL_KEYUP:
>				if(event.key.keysym.sym == SDLK_ESCAPE)
>				{
>					exit(0);
>				}
>				break;
>			case SDL_KEYDOWN:
>				break;
>			case SDL_MOUSEBUTTONDOWN:
>				break;
>			default:
>				break;
>		}
>	}
>}
>
>static inline bool IsKeyDown(int key)
>{
>	return (bool) SDL_GetKeyboardState(NULL)[key];
>}
>
>static inline void HandleKeys()
>{
>	if(IsKeyDown(SDL_SCANCODE_A))
>	{
>		WorldX += SCROLL_SPEED;
>	}
>	else if(IsKeyDown(SDL_SCANCODE_D))
>	{
>		WorldX -= SCROLL_SPEED;
>	}
>	if(IsKeyDown(SDL_SCANCODE_W))
>	{
>		WorldY -= SCROLL_SPEED;
>	}
>	else if(IsKeyDown(SDL_SCANCODE_S))
>	{
>		WorldY += SCROLL_SPEED;
>	}
>}
>
>static inline void DrawQuad(struct Rectf *bounds, struct Rectf *region)
>{
>	float minX = (bounds->x - HalfViewportW) * ViewportScaleW;
>	float minY = (bounds->y - HalfViewportH) * ViewportScaleH;
>	float maxX = ((bounds->x + bounds->w) - HalfViewportW) * ViewportScaleW;
>	float maxY = ((bounds->y + bounds->h) - HalfViewportH) * ViewportScaleH;
>	glBegin(GL_QUADS);
>		glTexCoord2f(region->x, region->y + region->h);
>		glVertex2f(minX, minY);
>
>		glTexCoord2f(region->x + region->w, region->y + region->h);
>		glVertex2f(maxX, minY);
>
>		glTexCoord2f(region->x + region->w, region->y);
>		glVertex2f(maxX, maxY);
>
>		glTexCoord2f(region->x, region->y);
>		glVertex2f(minX, maxY);
>	glEnd();
>}
>
>static inline void TileTexture(int cols, int rows)
>{
>	struct Rectf bounds = { WorldX, WorldY, TEXTURE_SIZE, TEXTURE_SIZE };
>	struct Rectf region = { 0, 0, 1, 1 };
>	for(int y = 0; y < rows; y++)
>	{
>		for(int x = 0; x < cols; x++)
>		{
>			DrawQuad(&bounds, &region);
>			bounds.x += TEXTURE_SIZE;
>		}
>		bounds.x = WorldX;
>		bounds.y += TEXTURE_SIZE;
>	}
>}
>
>int main(int argc, char const *argv[])
>{
>	InitSDL();
>	InitOpenGL();
>	InitTestTexture();
>	while(1)
>	{
>		HandleSDLEvents();
>		HandleKeys();
>		glClear(GL_COLOR_BUFFER_BIT);
>		TileTexture(TILE_COLS, TILE_ROWS);
>		SDL_GL_SwapWindow(RenderWindow);
>	}
>	return 0;
>}

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Attachments on bug 4067: 3157

We are currently migrating Bugzilla to GitHub issues.Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.